Presence API for PubNub Objective-C SDK

Presence enables you to track the online and offline status of users and devices in real time, as well as store custom state information. Presence provides authoritative information on:

  • When a user has joined or left a channel
  • Who, and how many, users are subscribed to a particular channel
  • Which channel(s) an individual user is subscribed to
  • Associated state information for these users

Learn more about our Presence feature here.

Here Now

Requires Presence add-onRequires that the Presence add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-

Description

You can obtain information about the current state of a channel including a list of unique user-ids currently subscribed to the channel and the total occupancy count of the channel by calling the hereNowForChannel function in your application.

Cache

This method has a 3 second response cache time.

Method(s)

To call Here Now you can use the following method(s) in the Objective-C SDK:

- (void)hereNowForChannel:(NSString *)channel withCompletion:(PNHereNowCompletionBlock)block;
ParameterTypeRequiredDescription
channelNSStringYesReference on channel for which here now information should be received.
blockPNHereNowCompletionBlockYesHere now processing completion block which pass two arguments: result - in case of successful request processing \c data field will contain results of here now operation; \c status - in case if error occurred during request processing.
 
- (void)hereNowForChannel:(NSString *)channel withVerbosity:(PNHereNowVerbosityLevel)level completion:(PNHereNowCompletionBlock)block;
ParameterTypeRequiredDescription
channelNSStringYesReference on channel for which here now information should be received.
levelPNHereNowVerbosityLevelYesReference on one of PNHereNowVerbosityLevel fields to instruct what exactly data it expected in response.
blockPNHereNowCompletionBlockYesHere now processing completion block which pass two arguments: result - in case of successful request processing \c data field will contain results of here now operation; \c status - in case if error occurred during request processing.

Basic Usage

Get a list of uuids subscribed to channel: 

// With PNHereNowUUID client will pull out list of unique identifiers and occupancy information.
[self.client hereNowForChannel: @"my_channel" withVerbosity:PNHereNowUUID
                    completion:^(PNPresenceChannelHereNowResult *result,
                                 PNErrorStatus *status) {

    // Check whether request successfully completed or not.
    if (!status) {

        /**
         Handle downloaded presence information using:
            result.data.uuids - list of uuids.
            result.data.occupancy - total number of active subscribers.
         */
    }
    else {

        /**
         Handle presence audit 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];
         */
    }
}];

Response

Response objects which is returned by client when Here Now API for channel used:

@interface PNPresenceGlobalHereNowData : PNServiceData

// Active channels list.
@property (nonatomic, readonly, strong) NSDictionary$lt;NSString *, NSDictionary *> *channels;
// Total number of active channels.
@property (nonatomic, readonly, strong) NSNumber *totalChannels;
// Total number of subscribers.
@property (nonatomic, readonly, strong) NSNumber *totalOccupancy;

@end

@interface PNPresenceChannelGroupHereNowData : PNPresenceGlobalHereNowData

@end

@interface PNPresenceChannelGroupHereNowResult : PNResult

// Stores reference on channel group presence request processing information.
@property (nonatomic, nonnull, readonly, strong) PNPresenceChannelGroupHereNowData *data;

@end

Other Examples

  1. Returning State: Requires Presence add-onRequires that the Presence add-on is enabled for your key. See this page on enabling add-on features on your keys:
    https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys- 

    /**
 With PNHereNowState client aside from occupancy and unique identifiers will will pull out
 state information associated with them.
 */
[self.client hereNowForChannel: @"my_channel" withVerbosity:PNHereNowState
                    completion:^(PNPresenceChannelHereNowResult *result,
                                 PNErrorStatus *status) {

    if (!status) {

        /**
         Handle downloaded presence information using:
            result.data.uuids - list of uuids. Each uuid entry will have next
                                fields: "uuid" - identifier and "state" if it
                                has been provided.
            result.data.occupancy - total number of active subscribers.
         */
    }
    else {

        /**
         Handle presence audit 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];
         */
    }
}];

    Example Response: 

    {
    "status" : 200,
    "message" : "OK",
    "service" : "Presence",
    "uuids" : [
        {
            "uuid" : "myUUID0"
        },
        {
            "state" : {
                "abcd" : {
                    "age" : 15
                }
            },
            "uuid" : "myUUID1"
        },
        {
            "uuid" : "b9eb408c-bcec-4d34-b4c4-fabec057ad0d"
        },
        {
            "state" : {
                "abcd" : {
                    "age" : 15
                }
            },
            "uuid" : "myUUID2"
        },
        {
            "state" : {
                "abcd" : {
                    "age" : 24
                }
            },
            "uuid" : "myUUID9"
        }
    ],
    "occupancy" : 5
}

  2. Return Occupancy Only: Requires Presence add-onRequires that the Presence add-on is enabled for your key. See this page on enabling add-on features on your keys:
    https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-

    You can return only the occupancy information for a single channel by specifying the channel and setting UUIDs to false:

    // With PNHereNowOccupancy client will pull out only occupancy information.
[self.client hereNowForChannel: @"my_channel" withVerbosity:PNHereNowOccupancy
                    completion:^(PNPresenceChannelHereNowResult *result,
                                 PNErrorStatus *status) {
    if (!status) {

        /**
         Handle downloaded presence information using:
            result.data.occupancy - total number of active subscribers.
         */
    }
    else {

        /**
         Handle presence audit 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];
         */
    }
}];

    Example Response: 

    {
    "status": 200,
    "message": "OK",
    "payload": {
        "channels": {
            "81d8d989-b95f-443c-a726-04fac323b331": {
                "uuids": [ "70fc1140-22b5-4abc-85b2-ff8c17b24d59" ],
                "occupancy": 1
            },
            "81b7a746-d153-49e2-ab70-3037a75cec7e": {
                "uuids": [ "91363e7f-584b-49cc-822c-52c2c01e5928" ],
                "occupancy": 1
            },
            "c068d15e-772a-4bcd-aa27-f920b7a4eaa8": {
                "uuids": [ "ccfac1dd-b3a5-4afd-9fd9-db11aeb65395" ],
                "occupancy": 1
            }
        },
        "total_channels": 3,
        "total_occupancy": 3
    },
    "service": "Presence"
}

Here Now for Channel Groups

Description

Request information about subscribers on specific channel group. This API method will retrieve the list of UUIDs along with their state for each remote data object and the number of subscribers.

Method(s)

To do Here Now for Channel Groups you can use the following method(s) in the Objective-C SDK:

- (void)hereNowForChannelGroup:(NSString *)group withCompletion:(PNChannelGroupHereNowCompletionBlock)block;
ParameterTypeRequiredDescription
groupNSStringYesReference on channel group for which here now information should be received.
blockPNChannelGroupHereNowCompletionBlockYesHere now processing completion block which pass two arguments: result - in case of successful request processing data field will contain results of here now operation; status - in case if error occurred during request processing.
 
- (void)hereNowForChannelGroup:(NSString *)group withVerbosity:(PNHereNowVerbosityLevel)level completion:(PNChannelGroupHereNowCompletionBlock)block;
ParameterTypeRequiredDescription
groupNSStringYesReference on channel group for which here now information should be received.
levelPNHereNowVerbosityLevelYesReference on one of PNHereNowVerbosityLevel fields to instruct what exactly data it expected in response.
blockPNChannelGroupHereNowCompletionBlockYesHere now processing completion block which pass two arguments: result - in case of successful request processing data field will contain results of here now operation; status - in case if error occurred during request processing.

Basic Usage

Here Now for Channel Groups: 

[self.client hereNowForChannelGroup:@"my_group"
                      withCompletion:^(PNPresenceChannelGroupHereNowResult *result,
                                       PNErrorStatus *status) {

    if (!status) {

        /**
         Handle downloaded presence information using:
            result.data.channels - dictionary with active channels and presence information on
                                   each. Each channel will have next fields: "uuids" - list of
                                   subscribers; occupancy - number of active subscribers.
                                   Each uuids entry has next fields: "uuid" - identifier and
                                   "state" if it has been provided.
            result.data.totalChannels - total number of active channels.
            result.data.totalOccupancy - total number of active subscribers.
         */
    }
    else {

        /**
         Handle presence audit 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()
         */
    }
 }];

Response

Response objects which is returned by client when Here Now API for channel group used:

@interface PNPresenceGlobalHereNowData : PNServiceData

// Active channels list.
@property (nonatomic, readonly, strong) NSDictionary$lt;NSString *, NSDictionary *> *channels;
// Total number of active channels.
@property (nonatomic, readonly, strong) NSNumber *totalChannels;
// Total number of subscribers.
@property (nonatomic, readonly, strong) NSNumber *totalOccupancy;

@end

@interface PNPresenceChannelGroupHereNowData : PNPresenceGlobalHereNowData

@end

@interface PNPresenceChannelGroupHereNowResult : PNResult

// Stores reference on channel group presence request processing information.
@property (nonatomic, nonnull, readonly, strong) PNPresenceChannelGroupHereNowData *data;

@end

Where Now

Requires Presence add-onRequires that the Presence add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-

Description

You can obtain information about the current list of channels to which a UUID is subscribed to by calling the whereNowUUID function in your application.

Note

If the app is killed/crashes and restarted (or the page containing the PubNub instance is refreshed on the browser) within the heartbeat window no timeout event is generated.

Method(s)

To call whereNowUUID you can use the following method(s) in the Objective-C SDK:

- (void)whereNowUUID:(NSString *)uuid withCompletion:(PNWhereNowCompletionBlock)block;
ParameterTypeRequiredDescription
uuidNSStringYesReference on UUID for which request should be performed.
blockPNWhereNowCompletionBlockYesWhere now processing completion block which pass two arguments: result - in case of successful request processing data field will contain results of where now operation; status - in case if error occurred during request processing.

Basic Usage

You simply need to define the uuid and the callback function to be used to send the data to as in the example below.

Get a list of channels a UUID is subscribed to: 

[self.client whereNowUUID:self.client.uuid withCompletion:^(PNPresenceWhereNowResult *result,
                                                            PNErrorStatus *status) {

    if (!status) {

        // Handle downloaded presence 'where now' information using: result.data.channels
    }
    else {

        /**
         Handle presence audit 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];
         */
    }
 }];

Response

Response objects which is returned by client when Where Now API is used:

@interface PNPresenceWhereNowData : PNServiceData

// List of channels on which client subscribed.
@property (nonatomic, readonly, strong) NSArray<NSString *> *channels;

@end

@interface PNPresenceWhereNowResult : PNResult

// Stores reference on client presence request processing information.
@property (nonatomic, readonly, strong) PNPresenceWhereNowData *data;

@end

User State

Requires Presence add-onRequires that the Presence add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-

Description

The state API is used to set/get key/value pairs specific to a subscriber uuid.

State information is supplied as a JSON object of key/value pairs.

Method(s)

Set State: 

- (void)setState:(nullable NSDictionary<NSString *, id> *)state forUUID:(NSString *)uuid onChannel:(NSString *)channel withCompletion:(nullable PNSetStateCompletionBlock)block;
ParameterTypeRequiredDescription
stateNSDictionaryNoReference on dictionary which should be bound to uuid on specified channel.If value is nil, state will be removed for uuid on channel.
uuidNSStringYesReference on unique user identifier for which state should be bound.
channelNSStringYesName of the channel which will store provided state information for uuid.
blockPNSetStateCompletionBlockNoState modification for user on channel processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.
 
- (void)setState:(nullable NSDictionary<NSString *, id> *)state forUUID:(NSString *)uuid onChannelGroup:(NSString *)group withCompletion:(nullable PNSetStateCompletionBlock)block;
ParameterTypeRequiredDescription
stateNSDictionaryNoReference on dictionary which should be bound to uuid on specified channel group.If value is nil, state will be removed for uuid on group.
uuidNSStringYesReference on unique user identifier for which state should be bound.
groupNSStringYesName of channel group which will store provided state information for uuid.
blockPNSetStateCompletionBlockNoState modification for user on channel processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Get State: 

- (void)stateForUUID:(NSString *)uuid onChannel:(NSString *)channel withCompletion:(PNChannelStateCompletionBlock)block;
ParameterTypeRequiredDescription
uuidNSStringYesReference on unique user identifier for which state should be retrieved.
channelNSStringYesName of channel from which state information for uuid will be pulled out.
blockPNChannelStateCompletionBlockYesState audition for user on cahnnel processing completion block which pass two arguments: result - in case of successful request processing data field will contain results of client state retrieve operation; status - in case if error occurred during request processing.
 
- (void)stateForUUID:(NSString *)uuid onChannelGroup:(NSString *)group withCompletion:(PNChannelGroupStateCompletionBlock)block;
ParameterTypeRequiredDescription
uuidNSStringYesReference on unique user identifier for which state should be retrieved.
groupNSStringYesName of channel group from which state information for uuid will be pulled out.
blockPNChannelGroupStateCompletionBlockYesState audition for user on cahnnel group processing completion block which pass two arguments: result - in case of successful request processing data field will contain results of client state retrieve operation; status - in case if error occurred during request processing.

Basic Usage

Set State : 

[self.client setState: @{@"Key": @"Value"} 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];
         */
    }
}];

Get State : 

[self.client stateForUUID:self.client.uuid onChannel:@"chat"
            withCompletion:^(PNChannelClientStateResult *result, PNErrorStatus *status) {

    if (!status) {

        // Handle downloaded state information using: result.data.state
    }
    else{

        /**
         Handle client state audit 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];
         */
    }
 }];

Response

Set State :

Response objects which is returned by client when Set State API for channels used:

@interface PNClientStateUpdateData : PNChannelClientStateData

@end

@interface PNClientStateUpdateStatus : PNErrorStatus

// Stores reference on client state for channel request processing information.
@property (nonatomic, nonnull, readonly, strong) PNClientStateUpdateData *data;

@end

Get State :

Response objects which is returned by client when Get State API for channel used:

@interface PNChannelClientStateData : PNServiceData

// User-provided client state information.
@property (nonatomic, readonly, strong) NSDictionary<NSString *, id> *state;

@end

@interface PNChannelClientStateResult : PNResult

// Stores reference on client state for channel request processing information.
@property (nonatomic, readonly, strong) PNChannelClientStateData *data;

@end

Response objects which is returned by client when Get State API for channel group used:

@interface PNChannelGroupClientStateData : PNServiceData

// Multi channel client state information.
@property (nonatomic, readonly, strong) NSDictionary<NSString *, NSDictionary *> *channels;

@end

@interface PNChannelGroupClientStateResult : PNResult

// Stores reference on client state for channel group request processing information.
@property (nonatomic, readonly, strong) PNChannelGroupClientStateData *data;

@end

User State (Builder Pattern)

Requires Presence add-onRequires that the Presence add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-

Description

The state API is used to set/get key/value pairs specific to a subscriber uuid.

State information is supplied as a JSON object of key/value pairs.

Method(s)

Set State: 

state().set().uuid(NSString *).state(NSDictionary *).channels(NSArray<NSString *> *).channelGroups(NSArray<NSString *> *).performWithCompletion(PNSetStateCompletionBlock)
ParameterTypeRequiredDescription
uuidNSStringNoUnique user identifier for which state should be bound. Current PubNub user ID will be used by default if not set or set to nil.
stateNSDictionaryNoData which should be bound to specified uuid on channels / channelGroups.
channelsNSArray<NSString *>NoList of the channel names which will store provided state information for uuid. Not required if channelGroups is set.
channelGroupsNSArray<NSString *>NoList of channel group names which will store provided state information for uuid. Not required if channels is set.
completionPNSetStateCompletionBlockNoState modification for user on channel / channel group completion block which pass only one argument - request status reports state change was successful or not (errorData contains error information in case of failure).
Note

This method uses the builder pattern, you can remove the arguments which are optional.

Get State: 

state().audit().uuid(NSString *).channels(NSArray<NSString *> *).channelGroups(NSArray<NSString *> *).performWithCompletion(PNGetStateCompletionBlock)
ParameterTypeRequiredDescription
uuidNSStringNoUnique user identifier for which state should be retrieved. Current PubNub user ID will be used by default if not set or set to nil.
channelsNSArray<NSString *>NoList of the channel names from which state information for uuid will be pulled out. Not required if channelGroups is set.
channelGroupsNSArray<NSString *>NoList of channel group names from which state information for uuid will be pulled out. Not required if channels is set.
completionPNGetStateCompletionBlockYesState audition for user on channel / channel group completion block which pass two arguments: result - in case of successful request processing data field will contain results of client state retrieve operation; status - in case of error occurred during request processing.
Note

This method uses the builder pattern, you can remove the arguments which are optional.

Basic Usage

Set State : 

self.client.state().set().state(@{@"state": @"test"})
    .channels(@[@"channel1", @"channel12"])
    .channelGroups(@[@"group1", @"group2"])
    .performWithCompletion(^(PNClientStateUpdateStatus *status) {

        if (!status.isError) {
            // Client state successfully modified on specified channels and groups.
        } 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]
            */
        }
    });

Get State : 

self.client.state().audit().uuid(@"PubNub")
    .channels(@[@"channel1", @"channel12"])
    .channelGroups(@[@"group1", @"group2"])
    .performWithCompletion(^(PNClientStateGetResult *result, PNErrorStatus *status) {

        if (!status.isError) {
            // Handle downloaded state information using: result.data.channels
        } else {
            /**
             Handle client state audit 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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