--- source_url: https://www.pubnub.com/docs/sdks/cocoa-objective-c/api-reference/publish-and-subscribe title: Publish/Subscribe API for Cocoa Objective-C SDK updated_at: 2026-06-18T11:27:17.214Z --- > Documentation Index > For a curated overview of PubNub documentation, see: https://www.pubnub.com/docs/llms.txt > For the full list of all documentation pages, see: https://www.pubnub.com/docs/llms-full.txt # Publish/Subscribe API for Cocoa Objective-C SDK ## Publish `publish()` sends a message to all channel subscribers. PubNub replicates the message and delivers it to all subscribed clients on that channel. To publish, set a valid `publishKey` at initialization. Secure messages with TLS/SSL by setting `ssl` to `true` during initialization. #### Publish anytime It's not required to be subscribed to a channel in order to publish to that channel. #### Message data The message can contain any JavaScript Object Notation (JSON)-serializable data (objects, arrays, integers, strings). Avoid Cocoa-specific classes or functions. Strings can include any UTF‑8 characters. :::warning Don't JSON serialize It is important to note that you should not JSON serialize when sending signals/messages via PUBNUB. Why? Because the serialization is done for you automatically. Instead just pass the full object as the message payload. PubNub takes care of everything for you. ::: #### Message size The maximum message size is 32 KiB, including the channel name and the escaped characters. Aim for under 1,800 bytes for optimal performance. If the message you publish exceeds the configured size, you will receive the following message: #### Message too large error ```objectivec ["PUBLISHED",[0,"Message Too Large","13524237335750949"]] ``` For further details, check [Calculating Message Payload Size Before Publish](https://support.pubnub.com/hc/en-us/articles/360051495932-Calculating-Message-Payload-Size-Before-Publish). :::tip Need larger messages? Our platform is optimized for payloads up to 32 KiB. PubNub supports larger messages, but increasing the limit requires a verification of compatibility with your use case. Talk to [our team](https://www.pubnub.com/company/contact-sales/) to discuss increasing the message size limit for your use case. ::: #### Message publish rate You can publish as fast as bandwidth allows. There is a soft throughput limit because messages may drop if subscribers can't keep up. For example, if 200 messages are published simultaneously before a subscriber has had a chance to receive any messages, the subscriber may not receive the first 100 messages because the message queue has a limit of only 100 messages stored in memory. #### Publishing to multiple channels It is not possible to publish a message to multiple channels simultaneously. The message must be published to one channel at a time. #### Publishing messages reliably There are some best practices to ensure messages are delivered when publishing to a channel: * Publish to any given channel in a serial manner (not concurrently). * Check that the return code is success (for example, `[1,"Sent","136074940..."]`) * Publish the next message only after receiving a success return code. * If a failure code is returned (`[0,"blah",""]`), retry the publish. * Avoid exceeding the in-memory queue's capacity of 100 messages. An overflow situation (aka missed messages) can occur if slow subscribers fail to keep up with the publish pace in a given period of time. * Throttle publish bursts in accordance with your app's latency needs, for example, Publish no faster than 5 msgs per second to any one channel. #### Publishing compressed messages Message compression lets you send the message payload as the compressed body of an HTTP POST call. Every PubNub SDK supports sending messages using the `publish()` call in one or more of the following ways: * Uncompressed, using HTTP GET (message sent in the URI) * Uncompressed, using HTTP POST (message sent in the body) * Compressed, using HTTP POST (compressed message sent in the body) This section outlines what compressing a message means, and how to use compressed messages to your advantage. :::note Suppport for compressed messages Currently, the C and Objective-C SDKs support compressed messages. ::: Message compression can be helpful if you want to send data exceeding the default 32 KiB message size limit, or use bandwidth more efficiently. Compressing messages is useful for scenarios that include high channel occupancy and quick exchange of information like ride hailing apps or multiplayer games. #### Compression trade-offs #### Small messages can expand Compressed messages generally have a smaller size, and can be delivered faster, but only if the original message is over 1 KiB. If you compress a signal (whose size is limited to 64 bytes), the compressed payload exceeds the signal's initial uncompressed size. #### CPU overhead can increase While a smaller payload size is an advantage, working with compressed messages uses more CPU time than working with uncompressed messages. CPU time is required to compress the message on the sending client, and again to decompress the message on the receiving client. Efficient resource management is especially important on mobile devices, where increased usage affects battery life. Carefully consider the balance of lower bandwidth and higher speed versus any increased CPU usage. #### Using compression Compression methods and support vary between SDKs. If the receiving SDK doesn't support the sender's compression method, or even if it doesn't support compression at all, the PubNub server automatically changes the compressed message's format so that it is understandable to the recipient. No action is necessary from you. Messages are not compressed by default; you must always explicitly specify that you want to use message compression. Refer to the code below for an example of sending a compressed message. ```objectivec [self.client publish:@{@"message": @"This message will be compressed"} toChannel:@"channel_name" compressed:YES withCompletion:^(PNPublishStatus *status) { if (!status.isError) { // Message successfully published to specified channel. } else { // Handle error. } }] ``` ### Method(s) To `Publish a message` you can use the following method(s) in the Cocoa SDK: #### Publish a message with block ```objectivec - (void)publish:(id)message toChannel:(NSString *)channel withCompletion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Type | Required | Default | Description | | --- | --- | --- | --- | --- | | message | id | Yes | | Reference on Foundation object ( `NSString`, `NSNumber`, `NSArray`, `NSDictionary`) which will be published. | | channel | NSString | Yes | | Reference on name of the `channel` to which `message` should be published. | | block | PNPublishCompletionBlock | Optional | | `Publish` processing completion `block` which pass only one argument - request processing status to report about how data pushing was successful or not. | #### Publish a message with compression and block ```objectivec - (void)publish:(id)message toChannel:(NSString *)channel compressed:(BOOL)compressed withCompletion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message` *Type: id | Reference on Foundation object (`NSString`, `NSNumber`, `NSArray`, `NSDictionary`) which will be published. | | `channel` *Type: NSString | Reference on name of the `channel` to which `message` should be published. | | `compressed` *Type: BOOL | Whether `message` should be `compressed` and sent with request body instead of URI part. Compression useful in case if large data should be published, in another case it will lead to packet size grow. | | `block`Type: PNPublishCompletionBlock | Publish processing completion `block` which pass only one argument - request processing status to report about how data pushing was successful or not. | #### Publish a message with storage and block ```objectivec - (void)publish:(id)message toChannel:(NSString *)channel storeInHistory:(BOOL)shouldStore withCompletion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message` *Type: id | Reference on Foundation `object` (`NSString`, `NSNumber`, `NSArray`,`NSDictionary`) which will be published. | | `channel` *Type: NSString | Reference on name of the `channel` to which `message` should be published. | | `shouldStore` *Type: BOOL | With `NO` this `message` later won't be fetched using Message Persistence API. | | `block`Type: PNPublishCompletionBlock | `Publish` processing completion `block` which pass only one argument - request processing status to report about how data pushing was successful or not. | #### Publish a message with storage, compression, and block ```objectivec - (void)publish:(id)message toChannel:(NSString *)channel storeInHistory:(BOOL)shouldStore compressed:(BOOL)compressed withCompletion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message` *Type: id | Reference on Foundation object (`NSString`, `NSNumber`, `NSArray`,`NSDictionary`) which will be published. | | `channel` *Type: NSString | Reference on name of the `channel` to which `message` should be published. | | `shouldStore` *Type: BOOL | With `NO` this `message` later won't be fetched using Message Persistence API. | | `compressed` *Type: BOOL | Compression useful in case if large data should be published, in another case it will lead to packet size grow. | | `block`Type: PNPublishCompletionBlock | `Publish` processing completion `block` which pass only one argument - request processing status to report about how data pushing was successful or not. | #### Publish a message with payload and block ```objectivec - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary *)payloads withCompletion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message`Type: id | Reference on Foundation `object` (`NSString`, `NSNumber`, `NSArray`, `NSDictionary`) which will be published. | | `channel` *Type: NSString | Reference on name of the `channel` to which `message` should be published. | | `payloads`Type: NSDictionary | Dictionary with payloads for different vendors (Apple with `apns` key and Google with `gcm`). | | `block`Type: PNPublishCompletionBlock | Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not. | #### Publish a message with payload, compression, and block ```objectivec - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary *)payloads compressed:(BOOL)compressed withCompletion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message`Type: id | Reference on Foundation `object` (`NSString`, `NSNumber`, `NSArray`, `NSDictionary`) which will be published. | | `channel` *Type: NSString | Reference on name of the `channel` to which `message` should be published. | | `payloads` *Type: NSDictionary | Dictionary with payloads for different vendors (Apple with `apns` key and Google with `gcm`). | | `compressed` *Type: BOOL | Compression useful in case if large data should be published, in another case it will lead to packet size grow. | | `block`Type: PNPublishCompletionBlock | Publish processing completion `block` which pass only one argument - request processing status to report about how data pushing was successful or not. | #### Publish a message with payload, storage, and block ```objectivec - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary *)payloads storeInHistory:(BOOL)shouldStore withCompletion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message`Type: id | Reference on Foundation `object` (`NSString`, `NSNumber`, `NSArray`,`NSDictionary`) which will be published. | | `channel` *Type: NSString | Reference on name of the `channel` to which `message` should be published. | | `payloads`Type: NSDictionary | Dictionary with payloads for different vendors (Apple with `apns` key and Google with `gcm`). | | `shouldStore` *Type: BOOL | With `NO` this `message` later won't be fetched using Message Persistence API. | | `block`Type: PNPublishCompletionBlock | Publish processing completion `block` which pass only one argument - request processing status to report about how data pushing was successful or not. | #### Publish a message with payload, storage, compression, and block ```objectivec - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary *)payloads storeInHistory:(BOOL)shouldStore compressed:(BOOL)compressed withCompletion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message`Type: id | Reference on Foundation `object` (`NSString`, `NSNumber`, `NSArray`,`NSDictionary`) which will be published. | | `channel` *Type: NSString | Reference on name of the `channel` to which message should be published. | | `payloads`Type: NSDictionary | Dictionary with payloads for different vendors (Apple with "apns" key and Google with "gcm"). | | `shouldStore` *Type: BOOL | With `NO` this `message` later won't be fetched using Message Persistence API. | | `compressed` *Type: BOOL | Compression useful in case if large data should be published, in another case it will lead to packet size grow. | | `block`Type: PNPublishCompletionBlock | Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not. | #### Publish a message with metadata and block ```objectivec - (void)publish:(id)message toChannel:(NSString *)channel withMetadata:(nullable NSDictionary *)metadata completion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message` *Type: id | The `message` may be any valid foundation `object` (`String`, `NSNumber`, `Array`, `Dictionary`). | | `channel` *Type: NSString | Specifies `channel` name to publish messages to. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | #### Publish a message with compression, metadata, and block ```objectivec - (void)publish:(id)message toChannel:(NSString *)channel compressed:(BOOL)compressed withMetadata:(nullable NSDictionary *)metadata completion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message` *Type: id | The `message` may be any valid foundation `object` (`String`, `NSNumber`, `Array`, `Dictionary`). | | `channel` *Type: NSString | Specifies `channel` name to publish messages to. | | `compressed` *Type: BOOL | If `true` the `message` will be `compressed` and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | #### Publish a message with storage, metadata, and block ```objectivec - (void)publish:(id)message toChannel:(NSString *)channel storeInHistory:(BOOL)shouldStore withMetadata:(nullable NSDictionary *)metadata completion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message` *Type: id | The `message` may be any valid foundation `object` (`String`, `NSNumber`, `Array`, `Dictionary`). | | `channel` *Type: NSString | Specifies `channel` name to publish messages to. | | `shouldStore` *Type: BOOL | If `false` the messages will not be stored in Message Persistence, default `true`. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | #### Publish a message with storage, compression, metadata, and block ```objectivec - (void)publish:(id)message toChannel:(NSString *)channel storeInHistory:(BOOL)shouldStore compressed:(BOOL)compressed withMetadata:(nullable NSDictionary *)metadata completion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message` *Type: id | The `message` may be any valid foundation `object` (`String`, `NSNumber`, `Array`, `Dictionary`). | | `channel` *Type: NSString | Specifies `channel` name to publish messages to. | | `shouldStore` *Type: BOOL | If `false` the messages will not be stored in Message Persistence, default `true`. | | `compressed` *Type: BOOL | If `true` the `message` will be `compressed` and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | #### Publish a message with payload, metadata, and block ```objectivec - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary *)payloads withMetadata:(nullable NSDictionary *)metadata completion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message`Type: id | The `message` may be any valid foundation `object` (`String`, `NSNumber`, `Array`, `Dictionary`). | | `channel` *Type: NSString | Specifies `channel` name to publish messages to. | | `payloads`Type: NSDictionary | Dictionary with `payloads` for different vendors (Apple with `aps` key and Google with `gcm`). Either payloads or `message` should be provided.. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | #### Publish a message with payload, compression, metadata, and block ```objectivec - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary *)payloads compressed:(BOOL)compressed withMetadata:(nullable NSDictionary *)metadata completion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message`Type: id | The `message` may be any valid foundation object (`String`, `NSNumber`, `Array`, `Dictionary`). | | `channel` *Type: NSString | Specifies `channel` name to `publish` messages to. | | `payloads`Type: NSDictionary | Dictionary with `payloads` for different vendors (Apple with `aps` key and Google with `gcm`). Either `payloads` or `message` should be provided. | | `compressed` *Type: BOOL | If `true` the `message` will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | #### Publish a message with payload, storage, metadata, and block ```objectivec - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary *)payloads storeInHistory:(BOOL)shouldStore withMetadata:(nullable NSDictionary *)metadata completion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message`Type: id | The `message` may be any valid foundation `object` (`String`, `NSNumber`, `Array`, `Dictionary`). | | `channel` *Type: NSString | Specifies `channel` name to publish messages to. | | `payloads`Type: NSDictionary | Dictionary with `payloads` for different vendors (Apple with `a ps` key and Google with `gcm`). Either `payloads` or `message` should be provided. | | `shouldStore` *Type: BOOL | If `false` the messages will not be stored in Message Persistence, default `true`. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | #### Publish a message with payload, storage, compression, metadata, and block ```objectivec - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary *)payloads storeInHistory:(BOOL)shouldStore compressed:(BOOL)compressed withMetadata:(nullable NSDictionary *)metadata completion:(nullable PNPublishCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message`Type: id | The `message` may be any valid foundation object (`String`, `NSNumber`, `Array`, `Dictionary`). | | `channel` *Type: NSString | Specifies `channel` name to `publish` messages to. | | `payloads`Type: NSDictionary | Dictionary with `payloads` for different vendors (Apple with `aps` key and Google with `gcm`). Either `payloads` or `message` should be provided. | | `shouldStore` *Type: BOOL | If `false` the messages will not be stored in Message Persistence, default `true`. | | `compressed` *Type: BOOL | If `true` the `message` will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | ### Sample code #### Publish a message to a channel ```objectivec [self.client publish: @{@"Dictionary": @[@"with",@"array",@"as", @"value"]} toChannel: @"pubnub" withCompletion:^(PNPublishStatus *status) { if (!status.isError) { // Message successfully published to specified channel. } else { /** Handle message publish error. Check 'category' property to find out possible reason because of which request did fail. Review 'errorData' property (which has PNErrorData data type) of status object to get additional information about issue. Request can be resent using: [status retry]; */ } }]; ``` :::note Subscribe to the channel Before running the above publish example, either using the [Debug Console](https://www.pubnub.com/docs/console/) or in a separate script running in a separate terminal window, [subscribe to the same channel](#subscribe) that is being published to. ::: ### Response Response objects which is returned by client when publish API is used: ```objectivec @interface PNPublishData : PNServiceData @property (nonatomic, readonly, strong) NSNumber *timetoken; @property (nonatomic, readonly, strong) NSString *information; @end @interface PNPublishStatus : PNAcknowledgmentStatus @property (nonatomic, readonly, strong) PNPublishData *data; @end ``` ### Other examples #### Publish with metadata ```objectivec [self publish: @"Hello from the PubNub Objective-C" toChannel:@"chat_channel" withMetadata: @{@"senderID" : @"bob"} completion:^(PNPublishStatus *status) { if (!status.isError) { // Message successfully published to specified channel. } else { /** Handle message publish error. Check 'category' property to find out possible reason because of which request did fail. Review 'errorData' property (which has PNErrorData data type) of status object to get additional information about issue. Request can be resent using: [status retry] */ } }]; ``` #### Push payload helper You can use the helper method as an input to the `Message` parameter, to format the payload for publishing [Push](https://www.pubnub.com/docs/general/push/send) messages. For more info on the helper method, check [Create Push Payload Helper Section](https://www.pubnub.com/docs/sdks/cocoa-objective-c/api-reference/misc#pnapnsnotificationconfiguration) ## Publish (builder pattern) This function publishes a message on a channel. :::note Optional arguments This method uses the builder pattern, you can remove the args which are optional. ::: ### Method(s) To run `Publish Builder` you can use the following method(s) in the Cocoa SDK: ```objectivec publish() .message(id) .channel(NSString *) .shouldStore(BOOL) .compress(BOOL) .ttl(NSUInteger) .payloads(NSDictionary *) .metadata(NSDictionary *) .performWithCompletion(nullable PNPublishCompletionBlock); ``` | Parameter | Description | | --- | --- | | `message`Type: id | The `message` may be any valid foundation object (`NSString`, `NSNumber`, `NSArray`, `NSDictionary`). | | `channel` *Type: NSString | Specifies `channel` name to `publish` messages to. | | `shouldStore`Type: BOOL | If `NO` the messages will not be stored in history. Default `YES`. | | `compress`Type: BOOL | If `YES` the `message` will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size. | | `ttl`Type: NSUInteger | Specify for how many hours published `message` should be stored. | | `payloads`Type: NSDictionary | Dictionary with `payloads` for different vendors (Apple with `aps` key and Google with `gcm`). Either `payloads` or `message` should be provided. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | ### Sample code Publish message which will be stored in channel's Message Persistence for next 16 hours. ```objectivec self.client.publish().channel(@"my_channel").message(@"Hello from PubNub iOS!").shouldStore(YES).ttl(16).performWithCompletion(^(PNPublishStatus *status) { if (!status.isError) { // Message successfully published to specified channel. } else { /** Handle message publish error. Check 'category' property to find out possible reason because of which request did fail. Review 'errorData' property (which has PNErrorData data type) of status object to get additional information about issue. Request can be resent using: [status retry]; */ } }); ``` ## Fire (builder pattern) The fire endpoint allows the client to send a message to BLOCKS Event Handlers. These messages will go directly to any Event Handlers registered on the channel that you fire to and will trigger their execution. The content of the fired request will be available for processing within the Event Handler. The message sent via `fire()` is not replicated, and so will not be received by any subscribers to the channel. The message is also not stored in history. :::note Optional arguments This method uses the builder pattern, you can remove the args which are optional. ::: ### Method(s) To `Fire a message` you can use the following method(s) in the Cocoa SDK: ```objectivec fire() .message(id) .channel(NSString *) .compress(BOOL) .payloads(NSDictionary *) .metadata(NSDictionary *) .performWithCompletion(nullable PNPublishCompletionBlock); ``` | Parameter | Description | | --- | --- | | `message`Type: id | The `message` may be any valid foundation object (`NSString`, `NSNumber`, `NSArray`, `NSDictionary`). | | `channel` *Type: NSString | Specifies `channel` name to `publish` messages to. | | `compress`Type: BOOL | If `YES` the `message` will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size. | | `payloads`Type: NSDictionary | Dictionary with `payloads` for different vendors (Apple with `aps` key and Google with `gcm`). Either `payloads` or `message` should be provided. | | `metadata`Type: NSDictionary | `NSDictionary` with values which should be used by `PubNub` service to filter messages. | | `block`Type: PNPublishCompletionBlock | The completion `block` which will be called when the processing is complete, has one argument: - `request` status reports the publish was successful or not (`errorData` contains error information in case of failure). | ### Sample code ```objectivec self.client.fire() .channel(@"my_channel") .message(@"Hello from PubNub iOS!") .shouldStore(YES) .performWithCompletion(^(PNPublishStatus *status) { if (!status.isError) { // Message successfully published to specified channel. } else { /** Handle message publish error. Check 'category' property to find out possible reason because of which request did fail. Review 'errorData' property (which has PNErrorData data type) of status object to get additional information about issue. Request can be resent using: [status retry]; */ } }); ``` ## Signal The `signal()` function is used to send a signal to all subscribers of a channel. By default, signals are limited to a message payload size of `64` bytes. This limit applies only to the payload, and not to the URI or headers. If you require a larger payload size, please [contact support](https://www.pubnub.com/docs/mailto:support@pubnub.com). ### Method(s) To `Signal a message` you can use the following method(s) in the Cocoa SDK: ```objectivec - (void)signal:(id)message channel:(NSString *)channel withCompletion:(nullable PNSignalCompletionBlock)block; ``` | Parameter | Description | | --- | --- | | `message` *Type: id | Object (`NSString`, `NSNumber`, `NSArray`, `NSDictionary`) which will be sent with signal. | | `channel` *Type: NSString | Name of the `channel` to which `signal` should be sent. | | `block`Type: PNSignalCompletionBlock | Signal processing completion `block` which pass only one argument - request processing status to report about how data pushing was successful or not. | ### Sample code #### Signal a message to a channel ```objectivec [self.client signal:@{ @"Hello": @"world" } channel:@"announcement" withCompletion:^(PNSignalStatus *status) { if (!status.isError) { // Signal successfully sent to specified channel. } else { /** * Handle signal sending error. Check 'category' property to find out possible issue * because of which request did fail. * * Request can be resent using: [status retry]; */ } }]; ``` ### Response Response objects returned by the client when Signal API is used: ```objectivec @interface PNSignalStatusData : PNServiceData @property (nonatomic, readonly, strong) NSNumber *timetoken; @property (nonatomic, readonly, strong) NSString *information; @end @interface PNSignalStatus : PNAcknowledgmentStatus @property (nonatomic, readonly, strong) PNSignalStatusData *data; @end ``` ## Signal (builder pattern) :::note Optional arguments This method uses the builder pattern, you can remove the args which are optional. ::: ### Method(s) To run `Signal Builder` you can use the following method(s) in the Cocoa SDK: ```objectivec signal() .message(id) .channel(NSString *) .performWithCompletion(nullable PNSignalCompletionBlock); ``` | Parameter | Description | | --- | --- | | `message` *Type: Array | Object (`NSString`, `NSNumber`, `NSArray`, `NSDictionary`) which will be sent with signal. | | `channel` *Type: String | Name of the `channel` to which `signal` should be sent. | | `block`Type: PNSignalCompletionBlock | Signal processing completion `block` which pass only one argument - request processing status to report about how data pushing was successful or not. | ### Sample code #### Signal a message to a channel ```objectivec self.client.signal() .message(@{ @"Hello": @"world" }).channel(@"announcement") .performWithCompletion(^(PNSignalStatus *status) { if (!status.isError) { // Signal successfully sent to specified channel. } else { /** * Handle signal sending error. Check 'category' property to find out possible issue * because of which request did fail. * * Request can be resent using: [status retry]; */ } }); ``` ### Response Response objects which is returned by client when Signal API is used:: ```objectivec @interface PNSignalStatusData : PNServiceData @property (nonatomic, readonly, strong) NSNumber *timetoken; @property (nonatomic, readonly, strong) NSString *information; @end @interface PNSignalStatus : PNAcknowledgmentStatus @property (nonatomic, readonly, strong) PNSignalStatusData *data; @end ``` ## Subscribe This function causes the client to create an open TCP socket to the PubNub Real-Time Network and begin listening for messages on a specified `channel`. To subscribe to a `channel` the client must send the appropriate `subscribeKey` at initialization. By default a newly subscribed client will only receive messages published to the channel after the `subscribeToChannels` call completes. :::tip Connectivity notification You can be notified of connectivity via the `connect` callback. By waiting for the connect callback to return before attempting to publish, you can avoid a potential race condition on clients that subscribe and immediately publish messages before the subscribe has completed. ::: Using Cocoa SDK, if a client becomes disconnected from a channel, it can automatically attempt to reconnect to that channel and retrieve any available messages that were missed during that period by setting `restore` to `YES`. By default a client will attempt to reconnect after exceeding a `320` second connection timeout. :::warning Unsubscribing from all channels **Unsubscribing** from all channels, and then **subscribing** to a new channel Y is not the same as subscribing to channel Y and then unsubscribing from the previously-subscribed channel(s). Unsubscribing from all channels resets the last-received `timetoken` and thus, there could be some gaps in the subscription that may lead to message loss. ::: ### Method(s) To `Subscribe to a channel` you can use the following method(s) in the Cocoa SDK: #### Subscribe to channels with Presence ```objectivec - (void)subscribeToChannels:(NSArray *)channels withPresence:(BOOL)shouldObservePresence; ``` | Parameter | Description | | --- | --- | | `channels` *Type: NSArray | List of `channel` names on which client should try to `subscribe`. | | `shouldObservePresence` *Type: BOOL | Whether presence observation should be enabled for `channels` or not. | #### Subscribe to channels with Presence and state ```objectivec - (void)subscribeToChannels:(NSArray *)channels withPresence:(BOOL)shouldObservePresence clientState:(nullable NSDictionary *)state; ``` | Parameter | Description | | --- | --- | | `channels` *Type: NSArray | List of `channel` names on which client should try to `subscribe`. | | `shouldObservePresence` *Type: BOOL | Whether presence observation should be enabled for `channels` or not. | | `state`Type: NSDictionary | Reference on dictionary which stores key-value pairs based on `channel` name and value which should be assigned to it. | #### Subscribe to channels with Presence and timetoken ```objectivec - (void)subscribeToChannels:(NSArray *)channels withPresence:(BOOL)shouldObservePresence usingTimeToken:(nullable NSNumber *)timeToken; ``` | Parameter | Description | | --- | --- | | `channels` *Type: NSArray | List of `channel` names on which client should try to `subscribe`. | | `shouldObservePresence` *Type: BOOL | Whether presence observation should be enabled for `channels` or not. | | `timeToken`Type: NSNumber | Specifies time from which to start returning any available cached messages. `Message` retrieval with `timetoken` is not guaranteed and should only be considered a best-effort service. | #### Subscribe to channels with Presence, timetoken, and state ```objectivec - (void)subscribeToChannels:(NSArray *)channels withPresence:(BOOL)shouldObservePresence usingTimeToken:(nullable NSNumber *)timeToken clientState:(nullable NSDictionary *)state; ``` | Parameter | Description | | --- | --- | | `channels` *Type: NSArray | List of `channel` names on which client should try to `subscribe`. | | `shouldObservePresence` *Type: BOOL | Whether presence observation should be enabled for `channels` or not. | | `timeToken`Type: NSNumber | Specifies time from which to start returning any available cached messages. `Message` retrieval with `timetoken` is not guaranteed and should only be considered a best-effort service. | | `state`Type: NSDictionary | Reference on dictionary which stores key-value pairs based on `channel` name and value which should be assigned to it. | ### Sample code Subscribe to a channel: ```objectivec /** Subscription results arrive to a listener which should implement the PNObjectEventListener protocol and be registered as follows: */ [self.client addListener:self]; [self.client subscribeToChannels: @[@"my_channel1", @"my_channel2"] withPresence:NO]; // Handle a new message from a subscribed channel - (void)client:(PubNub *)client didReceiveMessage:(PNMessageResult *)message { // Reference to the channel group containing the chat the message was sent to NSString *subscription = message.data.subscription; NSLog(@"%@ sent message to '%@' at %@: %@", message.data.publisher, message.data.channel, message.data.timetoken, message.data.message); } // Handle a subscription status change - (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status { if (status.operation == PNSubscribeOperation) { // Check to see if the message is about a successful subscription or restore if (status.category == PNConnectedCategory || status.category == PNReconnectedCategory) { // Status object for those categories can be cast to `PNSubscribeStatus` for use below. PNSubscribeStatus *subscribeStatus = (PNSubscribeStatus *)status; if (subscribeStatus.category == PNConnectedCategory) { // For a subscribe, this is expected, and means there are no errors or issues } else { // This usually occurs if there is a transient error. The subscribe fails but // then reconnects, and there is no longer any issue. } } else if (status.category == PNUnexpectedDisconnectCategory) { // This is usually an issue with the internet connection. // This is an error: handle appropriately, and retry will be called automatically. } // An issue occurred while the client tried to subscribe, // or the client was disconnected from the network else { PNErrorStatus *errorStatus = (PNErrorStatus *)status; if (errorStatus.category == PNAccessDeniedCategory) { // Access Manager prohibited this client from subscribing to this channel and channel group. // This is another explicit error. } else { /** You can directly specify more errors by creating explicit cases for other categories of `PNStatusCategory` errors, such as: - `PNDecryptionErrorCategory` - `PNMalformedFilterExpressionCategory` - `PNMalformedResponseCategory` - `PNTimeoutCategory` - `PNNetworkIssuesCategory` */ } } } else if (status.operation == PNUnsubscribeOperation) { if (status.category == PNDisconnectedCategory) { // This is the expected category for an unsubscribe. // There were no errors in unsubscribing from everything. } } else if (status.operation == PNHeartbeatOperation) { /** Heartbeat operations can have errors, so check first for an error. For more information on how to configure heartbeat notifications through the status PNObjectEventListener callback, refer to http://www.pubnub.com/docs/sdks/objective-c/api-reference/configuration#configuration_basic_usage */ if (!status.isError) { /* Heartbeat operation was successful */ } else { /* There was an error with the heartbeat operation: handle it here */ } } } // Handle a new signal from a subscribed channel - (void)client:(PubNub *)client didReceiveSignal:(PNSignalResult *)signal { NSLog(@"%@ sent signal to '%@' at %@: %@", message.data.publisher, message.data.channel, message.data.timetoken, message.data.message); } // Handle new object event from one of channels on which client has been subscribed. - (void)client:(PubNub *)client didReceiveObjectEvent:(PNObjectEventResult *)event { NSLog(@"'%@' has been %@'ed at %@", event.data.type, event.data.event, event.data.timestamp); } ``` ### Response ```objectivec @interface PNSubscriberData : PNServiceData // Name of channel on which subscriber received data. @property (nonatomic, readonly, strong) NSString *channel; // Name of channel or channel group (if not equal to channel name). @property (nonatomic, nullable, readonly, strong) NSString *subscription; // Time at which the event arrived. @property (nonatomic, readonly, strong) NSNumber *timetoken; // Stores a reference to the metadata information passed along with the received event. @property (nonatomic, nullable, readonly, strong) NSDictionary *userMetadata; @end @interface PNSubscribeStatus : PNErrorStatus // Timetoken used to establish the current subscription cycle. @property (nonatomic, readonly, strong) NSNumber *currentTimetoken; // Stores a reference to the previous key used in the subscription cycle to receive // currentTimetoken along with other events. @property (nonatomic, readonly, strong) NSNumber *lastTimeToken; // List of channels to which the client is currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannels; // List of channel group names to which the client is currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannelGroups; // Structured PNResult data field information. @property (nonatomic, readonly, strong) PNSubscriberData *data; @end // Message arrives to event listeners as model described below @interface PNMessageData : PNSubscriberData // Message sender identifier. @property (nonatomic, readonly, strong) NSString *publisher; // Message delivered through the data object live feed. @property (nonatomic, nullable, readonly, strong) id message; @end @interface PNMessageResult : PNResult // Stores a reference to the message object from live feed. @property (nonatomic, readonly, strong) PNMessageData *data; @end // Signal arrives to event listeners as model described below @interface PNSignalData : PNMessageData // Signal sender identifier. @property (nonatomic, readonly, strong) NSString *publisher; // Signal message delivered through the data object live feed. @property (nonatomic, nullable, readonly, strong) id message; @end @interface PNSignalResult : PNResult // Stores reference to signal object from live feed. @property (nonatomic, readonly, strong) PNSignalData *data; @end // Object events arrive to event listeners as model described below @interface PNObjectEventData : PNSubscriberData // This property will be set only if event 'type' is 'channel' and represent channel metadata. @property (nonatomic, nullable, readonly, strong) PNChannelMetadata *channelMetadata; // This property will be set only if event 'type' is 'uuid' and represent uuid metadata. @property (nonatomic, nullable, readonly, strong) PNUUIDMetadata *uuidMetadata; // This property will be set only if event `type` is 'membership' and represent uuid membership. @property (nonatomic, nullable, readonly, strong) PNMembership *membership; // Time when object event has been triggered. @property (nonatomic, readonly, strong) NSNumber *timestamp; // Name of action for which object event has been sent. @property (nonatomic, readonly, strong) NSString *event; // Type of object which has been changed and triggered event. @property (nonatomic, readonly, strong) NSString *type; @end @interface PNObjectEventResult : PNResult // Object event object from live feed. @property (nonatomic, readonly, strong) PNObjectEventData *data; @end // Message reaction events arrive to event listeners as model described below @interface PNMessageActionData : PNSubscriberData // Action for which event has been received. @property (nonatomic, readonly, strong) PNMessageAction *action; // Name of action for which message reaction event has been sent ('added') or ('removed') @property (nonatomic, readonly, copy) NSString *event; @end @interface PNMessageActionResult : PNResult // Message reaction object from live feed. @property (nonatomic, readonly, strong) PNMessageActionData *data; @end ``` ### Other examples #### Subscribing to a Presence channel :::warning Requires Presence This method requires that the Presence add-on is [enabled](https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-) for your key in the [Admin Portal](https://admin.pubnub.com/). ::: For any given channel there is an associated Presence channel. You can subscribe directly to the channel by appending `-pnpres` to the channel name. For example the channel named `my_channel` would have the presence channel named `my_channel-pnpres`. ```objectivec /** Subscription process results arrive to listener which should adopt to PNObjectEventListener protocol and registered using: */ [self.client addListener:self]; [self.client subscribeToPresenceChannels:@[@"my_channel"]]; // New presence event handling. - (void)client:(PubNub *)client didReceivePresenceEvent:(PNPresenceEventResult *)event { if (![event.data.channel isEqualToString:event.data.subscription]) { // Presence event has been received on channel group stored in event.data.subscription. } else { // Presence event has been received on channel stored in event.data.channel. } if (![event.data.presenceEvent isEqualToString:@"state-change"]) { NSLog(@"%@ \"%@'ed\"\nat: %@ on %@ (Occupancy: %@)", event.data.presence.uuid, event.data.presenceEvent, event.data.presence.timetoken, event.data.channel, event.data.presence.occupancy); } else { NSLog(@"%@ changed state at: %@ on %@ to: %@", event.data.presence.uuid, event.data.presence.timetoken, event.data.channel, event.data.presence.state); } } ``` #### Sample Responses #### Join event ```json { "action": "join", "timestamp": 1345546797, "uuid": "175c2c67-b2a9-470d-8f4b-1db94f90e39e", "occupancy": 2 } ``` ##### Leave event ```json { "action" : "leave", "timestamp" : 1345549797, "uuid" : "175c2c67-b2a9-470d-8f4b-1db94f90e39e", "occupancy" : 1 } ``` ##### Timeout event ```json { "action": "timeout", "timestamp": 1345549797, "uuid": "76c2c571-9a2b-d074-b4f8-e93e09f49bd", "occupancy": 0 } ``` ##### State change event ```json { "action": "state-change", "uuid": "76c2c571-9a2b-d074-b4f8-e93e09f49bd", "timestamp": 1345549797, "data": { "isTyping": true } } ``` ##### Interval event ```json { "action":"interval", "timestamp":1474396578, "occupancy":2 } ``` When a channel is in interval mode with `presence_deltas` `pnconfig` flag enabled, the interval message may also include the following fields which contain an array of changed UUIDs since the last interval message. * joined * left * timedout For example, this interval message indicates there were 2 new UUIDs that joined and 1 timed out UUID since the last interval: ```json { "action" : "interval", "occupancy" : <# users in channel>, "timestamp" : , "joined" : ["uuid2", "uuid3"], "timedout" : ["uuid1"] } ``` If the full interval message is greater than `30 KB` (since the max publish payload is `∼32 KiB`), none of the extra fields will be present. Instead there will be a `here_now_refresh` boolean field set to `true`. This indicates to the user that they should do a `hereNow` request to get the complete list of users present in the channel. ```json { "action" : "interval", "occupancy" : <# users in channel>, "timestamp" : , "here_now_refresh" : true } ``` #### Wildcard subscribe to channels :::note Requires Stream Controller add-on This method requires that the *Stream Controller* add-on is enabled for your key in the [Admin Portal](https://admin.pubnub.com/) (with Enable Wildcard Subscribe checked). Read the [support page](https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-) on enabling add-on features on your keys. ::: Wildcard subscribes allow the client to subscribe to multiple channels using wildcard. For example, if you subscribe to `a.*` you will get all messages for `a.b`, `a.c`, `a.x`. The wildcarded `*` portion refers to any portion of the channel string name after the `dot (.)`. ```objectivec [self.client subscribeToChannels: @[@"my_channel.*"] withPresence:YES]; ``` :::note Wildcard grants and revokes Only one level (`a.*`) of wildcarding is supported. If you grant on `*` or `a.b.*`, the grant will treat `*` or `a.b.*` as a single channel named either `*` or `a.b.*`. You can also revoke permissions from multiple channels using wildcards but only if you previously granted permissions using the same wildcards. Wildcard revokes, similarly to grants, only work one level deep, like `a.*`. ::: #### Subscribing with state This method requires that the *Presence* add-on is enabled for your key in the [Admin Portal](https://admin.pubnub.com/). Read the [support page](https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-) on enabling add-on features on your keys. ::: :::note Required UUID Always set the `UUID` to uniquely identify the user or device that connects to PubNub. This `UUID` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `UUID`, you won't be able to connect to PubNub. ::: ```objectivec // Initialize and configure PubNub client instance PNConfiguration *configuration = [PNConfiguration configurationWithPublishKey:@"demo" subscribeKey:@"demo"]; configuration.uuid = @"myUniqueUUID"; self.client = [PubNub clientWithConfiguration:configuration]; [self.client addListener:self]; // Subscribe to demo channel with presence observation [self.client subscribeToChannels: @[@"my_channel"] withPresence:YES]; - (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status { if (status.category == PNConnectedCategory) { [self.client setState: @{@"new": @"state"} forUUID:self.client.uuid onChannel: @"my_channel" withCompletion:^(PNClientStateUpdateStatus *status) { if (!status.isError) { // Client state successfully modified on specified channel. } else { /** Handle client state modification error. Check 'category' property to find out possible reason because of which request did fail. Review 'errorData' property (which has PNErrorData data type) of status object to get additional information about issue. Request can be resent using: [status retry]; */ } }]; } } // Handle new message from one of channels on which client has been subscribed. - (void)client:(PubNub *)client didReceiveMessage:(PNMessageResult *)message { // Handle new message stored in message.data.message if (![message.data.channel isEqualToString:message.data.subscription]) { // Message has been received on channel group stored in message.data.subscription. } else { // Message has been received on channel stored in message.data.channel. } NSLog(@"Received message: %@ on channel %@ at %@", message.data.message, message.data.channel, message.data.timetoken); } ``` ## Subscribe channel group :::note Requires Stream Controller add-on This method requires that the *Stream Controller* add-on is enabled for your key in the [Admin Portal](https://admin.pubnub.com/). Read the [support page](https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-) on enabling add-on features on your keys. ::: This functions subscribes to a channel group. ### Method(s) To `Subscribe to a Channel Group` you can use the following method(s) in the Cocoa SDK: #### Subscribe to channel groups with presence ```objectivec - (void)subscribeToChannelGroups:(NSArray *)groups withPresence:(BOOL)shouldObservePresence; ``` | Parameter | Description | | --- | --- | | `groups` *Type: NSArray | List of `channel` group names on which client should try to `subscribe`. | | `shouldObservePresence` *Type: BOOL | Whether presence observation should be enabled for `groups` or not. | #### Subscribe to channel groups with state ```objectivec - (void)subscribeToChannelGroups:(NSArray *)groups withPresence:(BOOL)shouldObservePresence clientState:(nullable NSDictionary *)state; ``` | Parameter | Description | | --- | --- | | `groups` *Type: NSArray | List of `channel` group names on which client should try to `subscribe`. | | `shouldObservePresence` *Type: BOOL | Whether presence observation should be enabled for `groups` or not. | | `state`Type: NSDictionary | Reference on dictionary which stores key-value pairs based on `channel` group name and value which should be assigned to it. | ### Sample code Subscribe to a channel group ```objectivec NSString *channelGroup = @"family"; ``` ```objectivec /** Subscription process results arrive to listener which should adopt to PNObjectEventListener protocol and registered using: */ [self.client addListener:self]; [self.client subscribeToChannelGroups:@[channelGroup] withPresence:NO]; // Handle new message from one of channels on which client has been subscribed. - (void)client:(PubNub *)client didReceiveMessage:(PNMessageResult *)message { // Handle new message stored in message.data.message if (![message.data.channel isEqualToString:message.data.subscription]) { // Message has been received on channel group stored in message.data.subscription. } else { // Message has been received on channel stored in message.data.channel. } NSLog(@"Received message: %@ on channel %@ at %@", message.data.message, message.data.channel, message.data.timetoken); } // Handle subscription status change. - (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status { if (status.operation == PNSubscribeOperation) { // Check whether received information about successful subscription or restore. if (status.category == PNConnectedCategory || status.category == PNReconnectedCategory) { // Status object for those categories can be casted to `PNSubscribeStatus` for use below. PNSubscribeStatus *subscribeStatus = (PNSubscribeStatus *)status; if (subscribeStatus.category == PNConnectedCategory) { // This is expected for a subscribe, this means there is no error or issue whatsoever. } else { /** This usually occurs if subscribe temporarily fails but reconnects. This means there was an error but there is no longer any issue. */ } } else if (status.category == PNUnexpectedDisconnectCategory) { /** This is usually an issue with the internet connection, this is an error, handle appropriately retry will be called automatically. */ } // Looks like some kind of issues happened while client tried to subscribe or disconnected from // network. else { PNErrorStatus *errorStatus = (PNErrorStatus *)status; if (errorStatus.category == PNAccessDeniedCategory) { /** This means that Access Manager does allow this client to subscribe to this channel and channel group configuration. This is another explicit error. */ } else { /** More errors can be directly specified by creating explicit cases for other error categories of `PNStatusCategory` such as: `PNDecryptionErrorCategory`, `PNMalformedFilterExpressionCategory`, `PNMalformedResponseCategory`, `PNTimeoutCategory` or `PNNetworkIssuesCategory` */ } } } } ``` ### Response ```objectivec @interface PNSubscriberData : PNServiceData // Name of channel for which subscriber received data. @property (nonatomic, readonly, strong) NSString *channel; // Name of channel or channel group (in case if not equal to channel). @property (nonatomic, nullable, readonly, strong) NSString *subscription; // Time at which event arrived. @property (nonatomic, readonly, strong) NSNumber *timetoken; // Stores reference on metadata information which has been passed along with received event. @property (nonatomic, nullable, readonly, strong) NSDictionary *userMetadata; @end @interface PNSubscribeStatus : PNErrorStatus // Timetoken which has been used to establish current subscription cycle. @property (nonatomic, readonly, strong) NSNumber *currentTimetoken; // Stores reference on previous key which has been used in subscription cycle to receive // currentTimetoken along with other events. @property (nonatomic, readonly, strong) NSNumber *lastTimeToken; // List of channels on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannels; // List of channel group names on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannelGroups; // Structured PNResult data field information. @property (nonatomic, readonly, strong) PNSubscriberData *data; @end // Message arrive to event listeners as model described below @interface PNMessageData : PNSubscriberData // Message sender identifier. @property (nonatomic, readonly, strong) NSString *publisher; // Message which has been delivered through data object live feed. @property (nonatomic, nullable, readonly, strong) id message; @end @interface PNMessageResult : PNResult // Stores reference on message object from live feed. @property (nonatomic, readonly, strong) PNMessageData *data; @end ``` ### Other examples #### Subscribe to the presence channel of a channel group :::note Requires Stream Controller and Presence add-ons This method requires both the *Stream Controller* and *Presence* add-ons are enabled for your key in the [Admin Portal](https://admin.pubnub.com/). Read the [support page](https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-) on enabling add-on features on your keys. ::: ```objectivec /** Subscription process results arrive to listener which should adopt to PNObjectEventListener protocol and registered using: */ [self.client addListener:self]; [self.client subscribeToChannelGroups:@[channelGroup] withPresence:YES]; // Handle new message from one of channels on which client has been subscribed. - (void)client:(PubNub *)client didReceiveMessage:(PNMessageResult *)message { // Handle new message stored in message.data.message if (![message.data.channel isEqualToString:message.data.subscription]) { // Message has been received on channel group stored in message.data.subscription. } else { // Message has been received on channel stored in message.data.channel. } NSLog(@"Received message: %@ on channel %@ at %@", message.data.message, message.data.channel, message.data.timetoken); } // New presence event handling. - (void)client:(PubNub *)client didReceivePresenceEvent:(PNPresenceEventResult *)event { if (![event.data.channel isEqualToString:event.data.subscription]) { // Presence event has been received on channel group stored in event.data.subscription. } else { // Presence event has been received on channel stored in event.data.channel. } if (![event.data.presenceEvent isEqualToString:@"state-change"]) { NSLog(@"%@ \"%@'ed\"\nat: %@ on %@ (Occupancy: %@)", event.data.presence.uuid, event.data.presenceEvent, event.data.presence.timetoken, event.data.channel, event.data.presence.occupancy); } else { NSLog(@"%@ changed state at: %@ on %@ to: %@", event.data.presence.uuid, event.data.presence.timetoken, event.data.channel, event.data.presence.state); } } // Handle subscription status change. - (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status { if (status.operation == PNSubscribeOperation) { // Check whether received information about successful subscription or restore. if (status.category == PNConnectedCategory || status.category == PNReconnectedCategory) { // Status object for those categories can be casted to `PNSubscribeStatus` for use below. PNSubscribeStatus *subscribeStatus = (PNSubscribeStatus *)status; if (subscribeStatus.category == PNConnectedCategory) { // This is expected for a subscribe, this means there is no error or issue whatsoever. } else { /** This usually occurs if subscribe temporarily fails but reconnects. This means there was an error but there is no longer any issue. */ } } else if (status.category == PNUnexpectedDisconnectCategory) { /** This is usually an issue with the internet connection, this is an error, handle appropriately retry will be called automatically. */ } // Looks like some kind of issues happened while client tried to subscribe or disconnected from // network. else { PNErrorStatus *errorStatus = (PNErrorStatus *)status; if (errorStatus.category == PNAccessDeniedCategory) { /** This means that Access Manager does allow this client to subscribe to this channel and channel group configuration. This is another explicit error. */ } else { /** More errors can be directly specified by creating explicit cases for other error categories of `PNStatusCategory` such as: `PNDecryptionErrorCategory`, `PNMalformedFilterExpressionCategory`, `PNMalformedResponseCategory`, `PNTimeoutCategory` or `PNNetworkIssuesCategory` */ } } } } ``` ## Unsubscribe When subscribed to a single channel, this function causes the client to issue a `leave` from the `channel` and close any open socket to the PubNub Network. For multiplexed channels, the specified `channel`(s) will be removed and the socket remains open until there are no more channels remaining in the list. :::warning Unsubscribing from all channels **Unsubscribing** from all channels, and then **subscribing** to a new channel Y is not the same as subscribing to channel Y and then unsubscribing from the previously-subscribed channel(s). Unsubscribing from all channels resets the last-received `timetoken` and thus, there could be some gaps in the subscription that may lead to message loss. ::: ### Method(s) To `Unsubscribe from a channel` you can use the following method(s) in the Cocoa SDK: ```objectivec - (void)unsubscribeFromChannels:(NSArray *)channels withPresence:(BOOL)shouldObservePresence; ``` | Parameter | Description | | --- | --- | | `channels` *Type: NSArray | List of `channel` names from which client should try to `unsubscribe`. | | `shouldObservePresence` *Type: BOOL | Whether client should disable presence observation on specified `channels` or keep listening for presence event on them. | ### Sample code Unsubscribe from a channel: ```objectivec /** Unsubscription process results arrive to listener which should adopt to PNObjectEventListener protocol and registered using: */ [self.client addListener:self]; [self.client unsubscribeFromChannels: @[@"my_channel1", @"my_channel2"] withPresence:NO]; // Handle subscription status change. - (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status { if (status.operation == PNUnsubscribeOperation && status.category == PNDisconnectedCategory) { /** This is the expected category for an unsubscribe. This means there was no error in unsubscribing from everything. */ } } ``` ### Response ```objectivec @interface PNSubscriberData : PNServiceData // Name of channel for which subscriber received data. @property (nonatomic, readonly, strong) NSString *channel; // Name of channel or channel group (in case if not equal to channel). @property (nonatomic, nullable, readonly, strong) NSString *subscription; // Time at which event arrived. @property (nonatomic, readonly, strong) NSNumber *timetoken; // Stores reference on metadata information which has been passed along with received event. @property (nonatomic, nullable, readonly, strong) NSDictionary *userMetadata; @end @interface PNSubscribeStatus : PNErrorStatus // Timetoken which has been used to establish current subscription cycle. @property (nonatomic, readonly, strong) NSNumber *currentTimetoken; // Stores reference on previous key which has been used in subscription cycle to receive // currentTimetoken along with other events. @property (nonatomic, readonly, strong) NSNumber *lastTimeToken; // List of channels on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannels; // List of channel group names on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannelGroups; // Structured PNResult data field information. @property (nonatomic, readonly, strong) PNSubscriberData *data; @end ``` ## Unsubscribe all Unsubscribe from all channels and all channel groups ### Method(s) ```objectivec - (void)unsubscribeFromAll; ``` ### Sample code ```objectivec /** Unsubscription process results arrive to listener which should adopt to PNObjectEventListener protocol and registered using: */ [self.client addListener:self]; [self.client unsubscribeFromAll]; // Handle subscription status change. - (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status { if (status.operation == PNUnsubscribeOperation && status.category == PNDisconnectedCategory) { /** This is the expected category for an unsubscribe. This means there was no error in unsubscribing from everything. */ } } ``` ### Returns None ## Unsubscribe from a channel group This function lets you Unsubscribe from a Channel Group ### Method(s) To run `Unsubscribe from a Channel Group` you can use the following method(s) in the Cocoa SDK: ```objectivec - (void)unsubscribeFromChannelGroups:(NSArray *)groups withPresence:(BOOL)shouldObservePresence; ``` | Parameter | Description | | --- | --- | | `groups` *Type: NSArray | List of `channel` group names from which client should try to `unsubscribe`. | | `shouldObservePresence` *Type: BOOL | Whether client should disable presence observation on specified `channel` groups or keep listening for presence event on them. | ### Sample code **Unsubscribe from a Channel Group:** [](#unsubscribe_from_channel_group_basic_usage_1) ```objectivec /** Unsubscription process results arrive to listener which should adopt to PNObjectEventListener protocol and registered using: */ [self.client addListener:self]; [self.client unsubscribeFromChannelGroups: @[@"developers"] withPresence:YES]; // Handle subscription status change. - (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status { if (status.operation == PNUnsubscribeOperation && status.category == PNDisconnectedCategory) { /** This is the expected category for an unsubscribe. This means there was no error in unsubscribing from everything. */ } } ``` ### Response ```objectivec @interface PNSubscriberData : PNServiceData // Name of channel for which subscriber received data. @property (nonatomic, readonly, strong) NSString *channel; // Name of channel or channel group (in case if not equal to channel). @property (nonatomic, nullable, readonly, strong) NSString *subscription; // Time at which event arrived. @property (nonatomic, readonly, strong) NSNumber *timetoken; // Stores reference on metadata information which has been passed along with received event. @property (nonatomic, nullable, readonly, strong) NSDictionary *userMetadata; @end @interface PNSubscribeStatus : PNErrorStatus // Timetoken which has been used to establish current subscription cycle. @property (nonatomic, readonly, strong) NSNumber *currentTimetoken; // Stores reference on previous key which has been used in subscription cycle to receive // currentTimetoken along with other events. @property (nonatomic, readonly, strong) NSNumber *lastTimeToken; // List of channels on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannels; // List of channel group names on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannelGroups; // Structured PNResult data field information. @property (nonatomic, readonly, strong) PNSubscriberData *data; @end ``` ## Presence This function is used to subscribe to the presence channel. Using Cocoa SDK, if a client becomes disconnected from a channel, it can automatically attempt to reconnect to that channel and retrieve any available messages that were missed during that period by setting `restore` to `true`. By default a client will attempt to reconnect after exceeding a `320` second connection timeout. ### Method(s) To do `Presence` you can use the following method(s) in the Cocoa SDK: ```objectivec - (void)subscribeToPresenceChannels:(NSArray *)channels; ``` | Parameter | Description | | --- | --- | | `channels` *Type: NSArray | List of `channel` names for which client should try to `subscribe` on presence observing `channels`. | ### Sample code Subscribe to the presence channel: For any given channel there is an associated `Presence` channel. You can subscribe directly to the channel by appending `-pnpres` to the channel name. For example the channel named `my_channel` would have the presence channel named `my_channel-pnpres` ```objectivec /** Subscription process results arrive to listener which should adopt to PNObjectEventListener protocol and registered using: */ [self.client addListener:self]; [self.client subscribeToPresenceChannels:@[@"my_channel"]]; // New presence event handling. - (void)client:(PubNub *)client didReceivePresenceEvent:(PNPresenceEventResult *)event { if (![event.data.channel isEqualToString:event.data.subscription]) { // Presence event has been received on channel group stored in event.data.subscription. } else { // Presence event has been received on channel stored in event.data.channel. } if (![event.data.presenceEvent isEqualToString:@"state-change"]) { NSLog(@"%@ \"%@'ed\"\nat: %@ on %@ (Occupancy: %@)", event.data.presence.uuid, event.data.presenceEvent, event.data.presence.timetoken, event.data.channel, event.data.presence.occupancy); } else { NSLog(@"%@ changed state at: %@ on %@ to: %@", event.data.presence.uuid, event.data.presence.timetoken, event.data.channel, event.data.presence.state); } } ``` ### Response ```objectivec @interface PNSubscriberData : PNServiceData // Name of channel for which subscriber received data. @property (nonatomic, readonly, strong) NSString *channel; // Name of channel or channel group (in case if not equal to channel). @property (nonatomic, nullable, readonly, strong) NSString *subscription; // Time at which event arrived. @property (nonatomic, readonly, strong) NSNumber *timetoken; // Stores reference on metadata information which has been passed along with received event. @property (nonatomic, nullable, readonly, strong) NSDictionary *userMetadata; @end @interface PNSubscribeStatus : PNErrorStatus // Timetoken which has been used to establish current subscription cycle. @property (nonatomic, readonly, strong) NSNumber *currentTimetoken; // Stores reference on previous key which has been used in subscription cycle to receive // currentTimetoken along with other events. @property (nonatomic, readonly, strong) NSNumber *lastTimeToken; // List of channels on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannels; // List of channel group names on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannelGroups; // Structured PNResult data field information. @property (nonatomic, readonly, strong) PNSubscriberData *data; @end // Presence events arrive to event listeners as model described below @interface PNPresenceDetailsData : PNSubscriberData // Time when presence event has been triggered. @property (nonatomic, readonly, strong) NSNumber *timetoken; // Reference on unique user identifier for which event has been triggered. @property (nonatomic, nullable, readonly, strong) NSString *uuid; // List of newly joined subscribers' UUID. @property (nonatomic, nullable, readonly, strong) NSArray *join; // List of recently leaved subscribers' UUID. @property (nonatomic, nullable, readonly, strong) NSArray *leave; // List of recently UUID of subscribers which leaved by timeout. @property (nonatomic, nullable, readonly, strong) NSArray *timeout; // Channel presence information. @property (nonatomic, readonly, strong) NSNumber *occupancy; // User changed client state. @property (nonatomic, nullable, readonly, strong) NSDictionary *state; @end @interface PNPresenceEventData : PNSubscriberData // Type of presence event. @property (nonatomic, readonly, strong) NSString *presenceEvent; // Additional presence information. @property (nonatomic, readonly, strong) PNPresenceDetailsData *presence; @end @interface PNPresenceEventResult : PNResult // Stores reference on presence event object from live feed. @property (nonatomic, readonly, strong) PNPresenceEventData *data; @end ``` ## Presence unsubscribe This function lets you stop monitoring the presence of the `channel`(s). The channel(s) will be removed and the socket remains open until there are no more channels remaining in the list. ### Method(s) To `Unsubscribe from Presence of a channel` you can use the following method(s) in the Cocoa SDK: ```objectivec - (void)unsubscribeFromPresenceChannels:(NSArray *)channels; ``` | Parameter | Description | | --- | --- | | `channels` *Type: NSArray | List of `channel` names for which client should try to `unsubscribe` from presence observing `channels` | ### Sample code Unsubscribe from the presence channel: ```objectivec [self.client unsubscribeFromChannelGroups:@[@"developers"] withPresence:YES]; ``` ### Response ```objectivec @interface PNSubscriberData : PNServiceData // Name of channel for which subscriber received data. @property (nonatomic, readonly, strong) NSString *channel; // Name of channel or channel group (in case if not equal to channel). @property (nonatomic, nullable, readonly, strong) NSString *subscription; // Time at which event arrived. @property (nonatomic, readonly, strong) NSNumber *timetoken; // Stores reference on metadata information which has been passed along with received event. @property (nonatomic, nullable, readonly, strong) NSDictionary *userMetadata; @end @interface PNSubscribeStatus : PNErrorStatus // Timetoken which has been used to establish current subscription cycle. @property (nonatomic, readonly, strong) NSNumber *currentTimetoken; // Stores reference on previous key which has been used in subscription cycle to receive // currentTimetoken along with other events. @property (nonatomic, readonly, strong) NSNumber *lastTimeToken; // List of channels on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannels; // List of channel group names on which client currently subscribed. @property (nonatomic, readonly, copy) NSArray *subscribedChannelGroups; // Structured PNResult data field information. @property (nonatomic, readonly, strong) PNSubscriberData *data; @end ``` ## Listeners You can be notified of connectivity status, message and presence notifications via the listeners. Listeners should be added before calling the method. #### Add listeners Listener's class should conform to `PNEventsListener` protocol to have access to available callbacks. ```objectivec // Adding listener. [pubnub addListener:self]; // Callbacks listed below. - (void)client:(PubNub *)pubnub didReceiveMessage:(PNMessageResult *)message { NSString *channel = message.data.channel; // Channel on which the message has been published NSString *subscription = message.data.subscription; // Wild-card channel or channel on which PubNub client actually subscribed NSNumber *timetoken = message.data.timetoken; // Publish timetoken id msg = message.data.message; // Message payload NSString *publisher = message.data.publisher; // Message publisher } - (void)client:(PubNub *)pubnub didReceiveSignal:(PNSignalResult *)signal { NSString *channel = message.data.channel; // Channel on which the signal has been published NSString *subscription = message.data.subscription; // Wild-card channel or channel on which PubNub client actually subscribed NSNumber *timetoken = message.data.timetoken; // Signal timetoken id msg = message.data.message; // Signal payload NSString *publisher = message.data.publisher; // Signal publisher } - (void)client:(PubNub *)pubnub didReceiveMessageAction:(PNMessageActionResult *)action { NSString *channel = action.data.channel; // Channel on which the message has been published NSString *subscription = action.data.subscription; // Wild-card channel or channel on which PubNub client actually subscribed NSString *event = action.data.event; // Can be: added or removed NSString *type = action.data.action.type; // Message reaction type NSString *value = action.data.action.value; // Message reaction value NSNumber *messageTimetoken = action.data.action.messageTimetoken; // Timetoken of the original message NSNumber *actionTimetoken = action.data.action.actionTimetoken; // Timetoken of the message reaction NSString *uuid = action.data.action.uuid; // UUID of user which added / removed message reaction } - (void)client:(PubNub *)pubnub didReceivePresenceEvent:(PNPresenceEventResult *)event { NSString *channel = message.data.channel; // Channel on which presence changes NSString *subscription = message.data.subscription; // Wild-card channel or channel on which PubNub client actually subscribed NSString *presenceEvent = event.data.presenceEvent; // Can be: join, leave, state-change, timeout or interval NSNumber *occupancy = event.data.presence.occupancy; // Number of users subscribed to the channel (not available for state-change event) NSNumber *timetoken = event.data.presence.timetoken; // Presence change timetoken NSString *uuid = event.data.presence.uuid; // UUID of user for which presence change happened // Only for 'state-change' event NSDictionary *state = event.data.presence.state; // User state (only for state-change event) // Only for 'interval' event NSArray *join = event.data.presence.join; // UUID of users which recently joined channel NSArray *leave = event.data.presence.leave; // UUID of users which recently leaved channel NSArray *timeout = event.data.presence.timeout; // UUID of users which recently timed out on channel } - (void)client:(PubNub *)pubnub didReceiveObjectEvent:(PNObjectEventResult *)event { NSString *channel = event.data.channel; // Channel to which the event belongs NSString *subscription = event.data.subscription; // Wild-card channel or channel on which PubNub client actually subscribed NSString *event = event.data.event; // Can be: set or delete NSString *type = event.data.type; // Entity type: channel, uuid or membership NSNumber *timestamp = event.data.timestamp; // Event timestamp PNChannelMetadata *channelMetadata = event.data.channelMetadata; // Updated channel metadata (only for channel entity type) PNUUIDMetadata *uuidMetadata = event.data.uuidMetadata; // Updated channel metadata (only for uuid entity type) PNMembership *membership = event.data.membership; // Updated channel metadata (only for membership entity type) } - (void)client:(PubNub *)pubnub didReceiveFileEvent:(PNFileEventResult *)event { NSString *channel = event.data.channel; // Channel to which file has been uploaded NSString *subscription = event.data.subscription; // Wild-card channel or channel on which PubNub client actually subscribed id message = event.data.message; // Message added for uploaded file NSString *publisher = event.data.publisher; // UUID of file uploader NSURL *fileDownloadURL = event.data.file.downloadURL; // URL which can be used to download file NSString *fileIdentifier = event.data.file.identifier; // Unique file identifier NSString *fileName = event.data.file.name; // Name with which file has been stored remotely } - (void)client:(PubNub *)pubnub didReceiveStatus:(PNStatus *)status { PNStatusCategory category = status.category; // One of PNStatusCategory fields to identify status of operation processing PNOperationType operation = status.operation; // One of PNOperationType fields to identify for which operation status received BOOL isError = status.isError; // Whether any kind of error happened. NSInteger statusCode = status.statusCode; // Related request processing status code BOOL isTLSEnabled = status.isTLSEnabled; // Whether secured connection enabled NSString *uuid = status.uuid; // UUID which configured for passed client NSString *authKey = status.authKey; // Auth key configured for passed client NSString *origin = status.origin; // Origin against which request has been sent NSURLRequest *clientRequest = status.clientRequest; // Request which has been used to send last request (may be nil) BOOL willAutomaticallyRetry = status.willAutomaticallyRetry; // Whether client will try to perform automatic retry // Following information available when operation == PNSubscribeOperation, because status is PNSubscribeStatus instance in this case PNSubscribeStatus *subscribeStatus = (PNSubscribeStatus *)status; NSNumber *currentTimetoken = subscribeStatus.currentTimetoken; // Timetoken which has been used for current subscribe request NSNumber *lastTimeToken = subscribeStatus.lastTimeToken; // Timetoken which has been used for previous subscribe request NSArray *subscribedChannels = subscribeStatus.subscribedChannels; // List of channels on which client currently subscribed NSArray *subscribedChannelGroups = subscribeStatus.subscribedChannelGroups; // List of channel groups on which client currently subscribed NSString *channel = subscribeStatus.data.channel; // Name of channel for which status has been received NSString *subscription = subscribeStatus.data.subscription; // Wild-card channel or channel on which PubNub client actually subscribed NSNumber *timetoken = subscribeStatus.data.timetoken; // Timetoken at which event arrived NSDictionary *userMetadata = subscribeStatus.data.userMetadata; // Metadata / envelope which has been passed along with event // Following information available when isError == YES, because status is PNErrorStatus instance in this case PNErrorStatus *errorStatus = (PNErrorStatus *)status; id associatedObject = errorStatus.associatedObject; // Data which may contain related information (not decrypted message for example) NSArray *erroredChannels = errorStatus.errorData.channels; // List of channels for which error reported (mostly because of Access Manager) NSArray *erroredChannelGroups = errorStatus.errorData.channelGroups; // List of channel groups for which error reported (mostly because of Access Manager) NSString *errorInformation = errorStatus.errorData.information; // Stringified information about error id errorData = errorStatus.errorData.data; // Additional error information from PubNub service } ``` #### Remove listeners ```objectivec [pubnub removeListener:self] ``` #### Handling disconnects SDK performs automated re-connections and call status handler to report back. This will happen forever, but user may decide to stop it. ```objectivec - (void)client:(PubNub *)pubnub didReceiveStatus:(PNStatus *)status { if (status.isError && status.willAutomaticallyRetry) { // Stop automatic retry attempts. [status cancelAutomaticRetry]; } } ``` #### Listener status events | Category | Description | | --- | --- | | `PNAcknowledgmentCategory` | An API call was successful. This status has additional details based on the type of the successful operation. | | `PNAccessDeniedCategory` | Access Manager permission failure. | | `PNTimeoutCategory` | Server didn't respond in time for reported operation request. | | `PNNetworkIssuesCategory` | No connection to Internet. | | `PNRequestMessageCountExceededCategory` | The SDK announces this error if `requestMessageCountThreshold` is set, and the number of messages received from PubNub (in-memory cache messages) exceeds the threshold. | | `PNConnectedCategory` | The SDK subscribed to new channels / channel groups. | | `PNReconnectedCategory` | The SDK was able to reconnect to PubNub. | | `PNDisconnectedCategory` | The SDK unsubscribed from channels / channel groups. | | `PNUnexpectedDisconnectCategory` | The SDK unexpectedly lost ability to receive live updated from PubNub. | | `PNRequestURITooLongCategory` | Reported operation request URI too long (too many channels / channel groups). | | `PNMalformedFilterExpressionCategory` | The SDK has been configured with malformed filtering expression. | | `PNMalformedResponseCategory` | The SDK received unexpected PubNub service response. | | `PNDecryptionErrorCategory` | The SDK unable to decrypt received message using configured `cipherKey`. | | `PNTLSConnectionFailedCategory` | The SDK unable to establish secured connection. | | `PNTLSUntrustedCertificateCategory` | The SDK unable to check certificates trust chain. |