Publish/Subscribe API for PubNub Cocoa Objective-C SDK

Publish

Description

The publish function is used to send a message to all subscribers of a channel. To publish a message you must first specify a valid publishKey at initialization. A successfully published message is replicated across the PubNub Real-Time Network and sent simultaneously to all subscribed clients on a channel.

Messages in transit can be secured from potential eavesdroppers with SSL/TLS 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 argument can contain any JSON serializable data, including: Objects, Arrays, Ints and Strings. data should not contain special Cocoa classes or functions as these will not serialize. String content can include any single-byte or multi-byte UTF-8 character.

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 number of characters per message is 32 KiB by default. The maximum message size is based on the final escaped character count, including the channel name. An ideal message size is under 1800 bytes which allows a message to be compressed and sent using single IP datagram (1.5 KiB) providing optimal network performance.

If the message you publish exceeds the configured size, you will receive the following message:

Message Too Large Error

["PUBLISHED",[0,"Message Too Large","13524237335750949"]]

For further details, check Calculating Message Payload Size Before Publish.

Message Publish Rate

Messages can be published as fast as bandwidth conditions will allow. There is a soft limit based on max throughput since messages will be discarded if the subscriber can't keep pace with the publisher.

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","<timetoken>"]), 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.

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.

[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:

  1. - (void)publish:(id)message toChannel:(NSString *)channel withCompletion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidYesReference on Foundation object ( NSString, NSNumber, NSArray, NSDictionary) which will be published.
    channelNSStringYesReference on name of the channel to which message should be published.
    blockPNPublishCompletionBlockNoPublish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.
  2. - (void)publish:(id)message toChannel:(NSString *)channel compressed:(BOOL)compressed withCompletion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidYesReference on Foundation object (NSString, NSNumber, NSArray, NSDictionary) which will be published.
    channelNSStringYesReference on name of the channel to which message should be published.
    compressedBOOLYesWhether 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.
    blockPNPublishCompletionBlockNoPublish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.
  3. - (void)publish:(id)message toChannel:(NSString *)channel storeInHistory:(BOOL)shouldStore withCompletion:(nullable PNPublishCompletionBlock)block
    ParameterTypeRequiredDescription
    messageidYesReference on Foundation object (NSString, NSNumber, NSArray,NSDictionary) which will be published.
    channelNSStringYesReference on name of the channel to which message should be published.
    shouldStoreBOOLYesWith NO this message later won't be fetched using Message Persistence API.
    blockPNPublishCompletionBlockNoPublish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.
  4. - (void)publish:(id)message toChannel:(NSString *)channel storeInHistory:(BOOL)shouldStore compressed:(BOOL)compressed withCompletion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidYesReference on Foundation object (NSString, NSNumber, NSArray,NSDictionary) which will be published.
    channelNSStringYesReference on name of the channel to which message should be published.
    shouldStoreBOOLYesWith NO this message later won't be fetched using Message Persistence API.
    compressedBOOLYesCompression useful in case if large data should be published, in another case it will lead to packet size grow.
    blockPNPublishCompletionBlockNoPublish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.
  5. - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads withCompletion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidNoReference on Foundation object (NSString, NSNumber, NSArray, NSDictionary) which will be published.
    channelNSStringYesReference on name of the channel to which message should be published.
    payloadsNSDictionaryNoDictionary with payloads for different vendors (Apple with apns key and Google with gcm).
    blockPNPublishCompletionBlockNoPublish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.
  6. - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads compressed:(BOOL)compressed withCompletion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidNoReference on Foundation object (NSString, NSNumber, NSArray, NSDictionary) which will be published.
    channelNSStringYesReference on name of the channel to which message should be published.
    payloadsNSDictionaryYesDictionary with payloads for different vendors (Apple with apns key and Google with gcm).
    compressedBOOLYesCompression useful in case if large data should be published, in another case it will lead to packet size grow.
    blockPNPublishCompletionBlockNoPublish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.
  7. - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads storeInHistory:(BOOL)shouldStore withCompletion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidNoReference on Foundation object (NSString, NSNumber, NSArray,NSDictionary) which will be published.
    channelNSStringYesReference on name of the channel to which message should be published.
    payloadsNSDictionaryNoDictionary with payloads for different vendors (Apple with apns key and Google with gcm).
    shouldStoreBOOLYesWith NO this message later won't be fetched using Message Persistence API.
    blockPNPublishCompletionBlockNoPublish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.
  8. - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads storeInHistory:(BOOL)shouldStore compressed:(BOOL)compressed withCompletion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidNoReference on Foundation object (NSString, NSNumber, NSArray,NSDictionary) which will be published.
    channelNSStringYesReference on name of the channel to which message should be published.
    payloadsNSDictionaryNoDictionary with payloads for different vendors (Apple with "apns" key and Google with "gcm").
    shouldStoreBOOLYesWith NO this message later won't be fetched using Message Persistence API.
    compressedBOOLYesCompression useful in case if large data should be published, in another case it will lead to packet size grow.
    blockPNPublishCompletionBlockNoPublish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.
  9. - (void)publish:(id)message toChannel:(NSString *)channel withMetadata:(nullable NSDictionary<NSString *, id> *)metadata completion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidYesThe message may be any valid foundation object (String, NSNumber, Array, Dictionary).
    channelNSStringYesSpecifies channel name to publish messages to.
    metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
    blockPNPublishCompletionBlockNoThe 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).
  10. - (void)publish:(id)message toChannel:(NSString *)channel compressed:(BOOL)compressed withMetadata:(nullable NSDictionary<NSString *, id> *)metadata completion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidYesThe message may be any valid foundation object (String, NSNumber, Array, Dictionary).
    channelNSStringYesSpecifies channel name to publish messages to.
    compressedBOOLYesIf 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.
    metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
    blockPNPublishCompletionBlockNoThe 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).
  11. - (void)publish:(id)message toChannel:(NSString *)channel storeInHistory:(BOOL)shouldStore withMetadata:(nullable NSDictionary<NSString *, id> *)metadata completion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidYesThe message may be any valid foundation object (String, NSNumber, Array, Dictionary).
    channelNSStringYesSpecifies channel name to publish messages to.
    shouldStoreBOOLYesIf false the messages will not be stored in history, default true.
    metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
    blockPNPublishCompletionBlockNoThe 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).
  12. - (void)publish:(id)message toChannel:(NSString *)channel storeInHistory:(BOOL)shouldStore compressed:(BOOL)compressed withMetadata:(nullable NSDictionary<NSString *, id> *)metadata completion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidYesThe message may be any valid foundation object (String, NSNumber, Array, Dictionary).
    channelNSStringYesSpecifies channel name to publish messages to.
    shouldStoreBOOLYesIf false the messages will not be stored in history, default true.
    compressedBOOLYesIf 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.
    metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
    blockPNPublishCompletionBlockNoThe 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).
  13. - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads withMetadata:(nullable NSDictionary<NSString *, id> *)metadata completion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidNoThe message may be any valid foundation object (String, NSNumber, Array, Dictionary).
    channelNSStringYesSpecifies channel name to publish messages to.
    payloadsNSDictionaryNoDictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided..
    metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
    blockPNPublishCompletionBlockNoThe 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).
  14. - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads compressed:(BOOL)compressed withMetadata:(nullable NSDictionary<NSString *, id> *)metadata completion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidNoThe message may be any valid foundation object (String, NSNumber, Array, Dictionary).
    channelNSStringYesSpecifies channel name to publish messages to.
    payloadsNSDictionaryNoDictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided.
    compressedBOOLYesIf 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.
    metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
    blockPNPublishCompletionBlockNoThe 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).
  15. - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads storeInHistory:(BOOL)shouldStore withMetadata:(nullable NSDictionary<NSString *, id> *)metadata completion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidNoThe message may be any valid foundation object (String, NSNumber, Array, Dictionary).
    channelNSStringYesSpecifies channel name to publish messages to.
    payloadsNSDictionaryNoDictionary with payloads for different vendors (Apple with a ps key and Google with gcm). Either payloads or message should be provided.
    shouldStoreBOOLYesIf false the messages will not be stored in history, default true.
    metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
    blockPNPublishCompletionBlockNoThe 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).
  16. - (void)publish:(nullable id)message toChannel:(NSString *)channel mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads storeInHistory:(BOOL)shouldStore compressed:(BOOL)compressed withMetadata:(nullable NSDictionary<NSString *, id> *)metadata completion:(nullable PNPublishCompletionBlock)block;
    ParameterTypeRequiredDescription
    messageidNoThe message may be any valid foundation object (String, NSNumber, Array, Dictionary).
    channelNSStringYesSpecifies channel name to publish messages to.
    payloadsNSDictionaryNoDictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided.
    shouldStoreBOOLYesIf false the messages will not be stored in history, default true.
    compressedBOOLYesIf 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.
    metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
    blockPNPublishCompletionBlockNoThe 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).

Basic Usage

Publish a message to a channel

[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.

show all 19 lines
Subscribe to the channel

Before running the above publish example, either using the Debug Console or in a separate script running in a separate terminal window, subscribe to the same channel that is being published to.

Response

Response objects which is returned by client when publish API is used:

@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

[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.

show all 19 lines

Push Payload Helper

You can use the helper method as an input to the Message parameter, to format the payload for publishing Push messages. For more info on the helper method, check Create Push Payload Helper Section

Publish (Builder Pattern)

Description

This function publishes a message on a channel.

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:

publish().message(id).channel(NSString *).shouldStore(BOOL).compress(BOOL).ttl(NSUInteger).payloads(NSDictionary *).metadata(NSDictionary *).performWithCompletion(PNPublishCompletionBlock);
ParameterTypeRequiredDescription
messageidNoThe message may be any valid foundation object (NSString, NSNumber, NSArray, NSDictionary).
channelNSStringYesSpecifies channel name to publish messages to.
shouldStoreBOOLNoIf NO the messages will not be stored in history.
Default YES.
compressBOOLNoIf 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.
ttlNSUIntegerNoSpecify for how many hours published message should be stored.
payloadsNSDictionaryNoDictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided.
metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
blockPNPublishCompletionBlockNoThe 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).

Basic Usage

Publish message which will be stored in channel's storage for next 16 hours.

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];
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Fire (Builder Pattern)

Description

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.

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:

fire().message(id).channel(NSString *).compress(BOOL).ttl(NSUInteger).payloads(NSDictionary *).metadata(NSDictionary *).performWithCompletion(PNPublishCompletionBlock);
ParameterTypeRequiredDescription
messageidNoThe message may be any valid foundation object (NSString, NSNumber, NSArray, NSDictionary).
channelNSStringYesSpecifies channel name to publish messages to.
compressBOOLNoIf 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.
ttlNSUIntegerNoSpecify for how many hours published message should be stored.
payloadsNSDictionaryNoDictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided.
metadataNSDictionaryNoNSDictionary with values which should be used by PubNub service to filter messages.
blockPNPublishCompletionBlockNoThe 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).

Basic Usage

self.client.fire().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];
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Signal

Description

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.

Method(s)

To Signal a message you can use the following method(s) in the Cocoa SDK:

(void)signal:(id)message channel:(NSString *)channel withCompletion:(nullable PNSignalCompletionBlock)block
ParameterTypeRequiredDescription
messageidYesObject (NSString, NSNumber, NSArray, NSDictionary) which will be sent with signal.
channelNSStringYesName of the channel to which signal should be sent.
blockPNSignalCompletionBlockNoSignal processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Basic Usage

Signal a message to a channel

[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:

@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)

Description

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:

signal().message(id).channel(NSString *).performWithCompletion(PNSignalCompletionBlock)
ParameterTypeRequiredDescription
messageArrayYesObject (NSString, NSNumber, NSArray, NSDictionary) which will be sent with signal.
channelStringYesName of the channel to which signal should be sent.
blockPNSignalCompletionBlockNoSignal processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Basic Usage

Signal a message to a channel

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::

@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

Description

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.

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.

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:

  1. - (void)subscribeToChannels:(NSArray<NSString *> *)channels withPresence:(BOOL)shouldObservePresence;
    ParameterTypeRequiredDescription
    channelsNSArrayYesList of channel names on which client should try to subscribe.
    shouldObservePresenceBOOLYesWhether presence observation should be enabled for channels or not.
  2. - (void)subscribeToChannels:(NSArray<NSString *> *)channels withPresence:(BOOL)shouldObservePresence clientState:(nullable NSDictionary<NSString *, id> *)state;
    ParameterTypeRequiredDescription
    channelsNSArrayYesList of channel names on which client should try to subscribe.
    shouldObservePresenceBOOLYesWhether presence observation should be enabled for channels or not.
    stateNSDictionaryNoReference on dictionary which stores key-value pairs based on channel name and value which should be assigned to it.
  3. - (void)subscribeToChannels:(NSArray<NSString *> *)channels withPresence:(BOOL)shouldObservePresence usingTimeToken:(nullable NSNumber *)timeToken;
    ParameterTypeRequiredDescription
    channelsNSArrayYesList of channel names on which client should try to subscribe.
    shouldObservePresenceBOOLYesWhether presence observation should be enabled for channels or not.
    timeTokenNSNumberNoSpecifies 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.
  4. - (void)subscribeToChannels:(NSArray<NSString *> *)channels withPresence:(BOOL)shouldObservePresence usingTimeToken:(nullable NSNumber *)timeToken clientState:(nullable NSDictionary<NSString *, id> *)state;
    ParameterTypeRequiredDescription
    channelsNSArrayYesList of channel names on which client should try to subscribe.
    shouldObservePresenceBOOLYesWhether presence observation should be enabled for channels or not.
    timeTokenNSNumberNoSpecifies 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.
    stateNSDictionaryNoReference on dictionary which stores key-value pairs based on channel name and value which should be assigned to it.

Basic Usage

Subscribe to a channel:

/**
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);
}

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Response

@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<NSString *, id> *userMetadata;

@end
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Other Examples

Subscribing to a Presence channel

Requires Presence add-on

This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

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.

/**
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 {
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Sample Responses

Join Event

{
"action": "join",
"timestamp": 1345546797,
"uuid": "175c2c67-b2a9-470d-8f4b-1db94f90e39e",
"occupancy": 2
}
Leave Event
{
"action" : "leave",
"timestamp" : 1345549797,
"uuid" : "175c2c67-b2a9-470d-8f4b-1db94f90e39e",
"occupancy" : 1
}
Timeout Event
{
"action": "timeout",
"timestamp": 1345549797,
"uuid": "76c2c571-9a2b-d074-b4f8-e93e09f49bd",
"occupancy": 0
}
Custom Presence Event (State Change)
{
"action": "state-change",
"uuid": "76c2c571-9a2b-d074-b4f8-e93e09f49bd",
"timestamp": 1345549797,
"data": {
"isTyping": true
}
}
Interval Event
{
"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:

{
"action" : "interval",
"occupancy" : <# users in channel>,
"timestamp" : <unix timestamp>,
"joined" : ["uuid2", "uuid3"],
"timedout" : ["uuid1"]
}

If the full interval message is greater than 30KB (since the max publish payload is ∼32KB), 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.

{
"action" : "interval",
"occupancy" : <# users in channel>,
"timestamp" : <unix timestamp>,
"here_now_refresh" : true
}

Wildcard subscribe to channels

Requires Stream Controller add-on

This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal (with Enable Wildcard Subscribe checked). Read the support page 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 (.).

[self.client subscribeToChannels: @[@"my_channel.*"] withPresence:YES];
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. Read the support page on enabling add-on features on your keys. :::

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.

// 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) {

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Subscribe Channel Group

Requires Stream Controller add-on

This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

Description

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:

  1. - (void)subscribeToChannelGroups:(NSArray<NSString *> *)groups withPresence:(BOOL)shouldObservePresence;
    ParameterTypeRequiredDescription
    groupsNSArrayYesList of channel group names on which client should try to subscribe.
    shouldObservePresenceBOOLYesWhether presence observation should be enabled for groups or not.
  2. - (void)subscribeToChannelGroups:(NSArray<NSString *> *)groups withPresence:(BOOL)shouldObservePresence clientState:(nullable NSDictionary<NSString *, id> *)state;
    ParameterTypeRequiredDescription
    groupsNSArrayYesList of channel group names on which client should try to subscribe.
    shouldObservePresenceBOOLYesWhether presence observation should be enabled for groups or not.
    stateNSDictionaryNoReference on dictionary which stores key-value pairs based on channel group name and value which should be assigned to it.

Basic Usage

Subscribe to a channel group

NSString *channelGroup = @"family";
/**
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.
}
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Response

@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<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Other Examples

Subscribe to the presence channel of a channel group

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. Read the support page on enabling add-on features on your keys.

/**
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.
}
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Unsubscribe

Description

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.

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:

- (void)unsubscribeFromChannels:(NSArray<NSString *> *)channels withPresence:(BOOL)shouldObservePresence;
ParameterTypeRequiredDescription
channelsNSArrayYesList of channel names from which client should try to unsubscribe.
shouldObservePresenceBOOLYesWhether client should disable presence observation on specified channels or keep listening for presence event on them.

Basic Usage

Unsubscribe from a channel:

/**
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.
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Response

@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<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Unsubscribe All

Description

Unsubscribe from all channels and all channel groups

Method(s)

- (void)unsubscribeFromAll;

Basic Usage

/**
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.
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Returns

None

Unsubscribe from a Channel Group

Description

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:

- (void)unsubscribeFromChannelGroups:(NSArray<NSString *> *)groups withPresence:(BOOL)shouldObservePresence;
ParameterTypeRequiredDescription
groupsNSArrayYesList of channel group names from which client should try to unsubscribe.
shouldObservePresenceBOOLYesWhether client should disable presence observation on specified channel groups or keep listening for presence event on them.

Basic Usage

Unsubscribe from a Channel Group:

/**
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.
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Response

@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<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Presence

Description

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:

- (void)subscribeToPresenceChannels:(NSArray<NSString *> *)channels;
ParameterTypeRequiredDescription
channelsNSArrayYesList of channel names for which client should try to subscribe on presence observing channels.

Basic Usage

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

/**
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 {
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Response

@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<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Presence Unsubscribe

Description

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:

- (void)unsubscribeFromPresenceChannels:(NSArray<NSString *> *)channels;
ParameterTypeRequiredDescription
channelsNSArrayYesList of channel names for which client should try to unsubscribe from presence observing channels

Basic Usage

Unsubscribe from the presence channel:

[self.client unsubscribeFromChannelGroups:@[@"developers"] withPresence:YES];

Response

@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<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Listeners

Description

You can be notified of connectivity status, message and presence notifications via the listeners.

Listeners should be added before calling the method.

Adding Listeners

Listener's class should conform to PNEventsListener protocol to have access to available callbacks.

// 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
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Removing Listeners

[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.

- (void)client:(PubNub *)pubnub didReceiveStatus:(PNStatus *)status {
if (status.isError && status.willAutomaticallyRetry) {
// Stop automatic retry attempts.
[status cancelAutomaticRetry];
}
}

Listener status events

CategoryDescription
PNAcknowledgmentCategoryReported operation request acknowledgment status.
PNAccessDeniedCategoryAccess Manager permission failure.
PNTimeoutCategoryServer didn't respond in time for reported operation request.
PNNetworkIssuesCategoryNo connection to Internet.
PNRequestMessageCountExceededCategoryThe SDK announces this error if requestMessageCountThreshold is set, and the number of messages received from PubNub (in-memory cache messages) exceeds the threshold.
PNConnectedCategoryThe SDK subscribed to new channels / channel groups.
PNReconnectedCategoryThe SDK was able to reconnect to PubNub.
PNDisconnectedCategoryThe SDK unsubscribed from channels / channel groups.
PNUnexpectedDisconnectCategoryThe SDK unexpectedly lost ability to receive live updated from PubNub.
PNRequestURITooLongCategoryReported operation request URI too long (too many channels / channel groups).
PNMalformedFilterExpressionCategoryThe SDK has been configured with malformed filtering expression.
PNMalformedResponseCategoryThe SDK received unexpected PubNub service response.
PNDecryptionErrorCategoryThe SDK unable to decrypt received message using configured cipherKey.
PNTLSConnectionFailedCategoryThe SDK unable to establish secured connection.
PNTLSUntrustedCertificateCategoryThe SDK unable to check certificates trust chain.