Presence API for PubNub Swift Native SDK

Note

The PubNub Swift 3.0 SDK contains many significant changes from the 2.x SDK, including breaking changes. Please refer to the PubNub Swift 3.0 Migration Guide for more details.

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-on Requires 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 hereNow() 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 Swift SDK:

hereNow(  on channels: [String],  and groups: [String] = [],  includeUUIDs: Bool = true,  includeState: Bool = false,  custom requestConfig: RequestConfiguration = RequestConfiguration(),  completion: ((Result<[String: PubNubPresence], Error>) -> Void)?)

Parameter	Type	Required	Default	Description
`on`	[String]	Yes		The list of `channels` to return occupancy results from.
`and`	[String]	Optional	`[]`	The list of `channel groups` for which will return occupancy results from.
`includeUUIDs`	Bool	Optional	`true`	Setting `uuid` to `false` disables the return of UUIDs.
`includeState`	Bool	Optional	`false`	Setting this flag to `true` will return the subscribe state information as well.
`custom`	RequestConfiguration	Optional	`RequestConfiguration()`	An object that allows for per-request customization of PubNub Configuration or Network Session
`completion`	((Result<[String: PubNubPresence], Error>) -> Void)?	Optional	`nil`	The async `Result` of the method call

Completion Handler Result

Success A Dictionary of channels mapped to their respective PubNubPresence

public protocol PubNubPresence {
    /// The channel identifier
    var channel: String { get }

    /// The total number of UUIDs present on the channel
    var occupancy: Int { get set }

    /// The known UUIDs present on the channel
    ///
    /// The `count` of this Array may differ from the `occupancy` field
    var occupants: [String] { get set }

    /// The Dictionary of UUIDs mapped to their respective presence state data
    var occupantsState: [String: JSONCodable] { get set }
  }

Failure An Error describing the failure

Basic Usage

Get a list of UUIDs subscribed to channel:

pubnub.hereNow(on: ["my_channel"]) { result in
  switch result {
  case let .success(presenceByChannel):
    print("Total channels \(presenceByChannel.totalChannels)")
    print("Total occupancy across all channels \(presenceByChannel.totalOccupancy)")
    if let myChannelPresence = presenceByChannel["my_channel"] {
      print("The occupancy for `my_channel` is \(myChannelPresence.occupancy)")
      print("The list of occupants for `my_channel` are \(myChannelPresence.occupants)")
    }
  case let .failure(error):
    print("Failed hereNow Response: \(error.localizedDescription)")
  }
})

Other Examples

Return Occupancy Only:

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

pubnub.hereNow(
  on: ["my-channel"],
  includeUUIDs: false
) { result in
  switch result {
  case let .success(presenceByChannel):
    if let myChannelPresence = presenceByChannel["my_channel"] {
      print("The occupancy for `my_channel` is \(myChannelPresence.occupancy)")
    }
  case let .failure(error):
    print("Failed hereNow Response: \(error.localizedDescription)")
  }
}

Channel Group Usage :

pubnub.hereNow(
  on: [],
  and: ["my-channel-group"]
) { result in
  switch result {
  case let .success(presenceByChannel):
    print("The `Dictionary` of channels mapped to their respective `PubNubPresence`: \(presenceByChannel)")
  case let .failure(error):
    print("Failed hereNow Response: \(error.localizedDescription)")
  }
}

Where Now

Description

You can obtain information about the current list of channels to which a UUID is subscribed to by calling the whereNow() 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 whereNow() you can use the following method(s) in the Swift SDK:

whereNow(  for uuid: String,  custom requestConfig: RequestConfiguration = RequestConfiguration(),  completion: ((Result<[String: [String]], Error>) -> Void)?)

Parameter	Type	Required	Default	Description
`for`	String	Yes		Specifies the `UUID` to return channel list for.
`custom`	RequestConfiguration	Optional	`RequestConfiguration()`	An object that allows for per-request customization of PubNub Configuration or Network Session
`completion`	((Result<[String: [String]], Error>) -> Void)?	Optional	`nil`	The async `Result` of the method call

Completion Handler Result

Success A Dictionary of UUIDs mapped to their respective Array of channels they have presence on
Failure An Error describing the failure

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:

pubnub.whereNow(for: "my-unique-uuid") { result in
  switch result {
  case let .success(channelsByUUID):
    print("A `Dictionary` of UUIDs mapped to their respective `Array` of channels they have presence on \(channelsByUUID)")
    if let channels = channelsByUUID["my-unique-uuid"] {
      print("The list of channel identifiers for the UUID `my-unique-uuid`: \(channels)")
    }
  case let .failure(error):
    print("Failed WhereNow Response: \(error.localizedDescription)")
  }
}

User State

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:

setPresence(  state: [String: JSONCodableScalar],  on channels: [String],  and groups: [String] = [],  custom requestConfig: RequestConfiguration = RequestConfiguration(),  completion: ((Result<JSONCodable, Error>) -> Void)?)

Parameter	Type	Required	Default	Description
`state`	[String: JSONCodableScalar]	Yes		The `state` Dictionary to store. Nesting of Dictionary values isn't permitted, and key names beginning with prefix `pn` are reserved. Setting the `state` will overwrite the previous values set. Clearing out the `state` involves passing in an empty Dictionary
`on`	[String]	No		The list of channel to set the state on. Pass an empty array to not set.
`and`	[String]	No		The list of channel groups to set the state on.
`custom`	RequestConfiguration	Optional	`RequestConfiguration()`	An object that allows for per-request customization of PubNub Configuration or Network Session
`completion`	((Result<JSONCodable, Error>) -> Void)?	Optional	`nil`	The async `Result` of the method call

Completion Handler Result

Success The presence State set as a JSONCodable
Failure An Error describing the failure

Get State:

getPresenceState(  for uuid: String,  on channels: [String],  and groups: [String],  custom requestConfig: RequestConfiguration = RequestConfiguration(),  completion: ((Result<(uuid: String, stateByChannel: [String: JSONCodable]), Error>) -> Void)?)

Parameter	Type	Required	Default	Description
`for`	String	Yes		The UUID to retrieve the state for.
`on`	[String]	No		The list of channel to get the state on. Pass an empty array to not get.
`and`	[String]	No	[]
`custom`	RequestConfiguration	Optional	`RequestConfiguration()`	An object that allows for per-request customization of PubNub Configuration or Network Session
`completion`	((Result<(uuid: String, stateByChannel: [String: JSONCodable]), Error>) -> Void)?	Optional	`nil`	The async `Result` of the method call

Completion Handler Result

Success A Tuple containing the UUID that set the State and a Dictionary of channels mapped to their respective State
Failure An Error describing the failure

Basic Usage

Set State :

pubnub.setPresence(
  state: ["new": "state"],
  on: ["channelSwift"],
  and: ["demo"]
) { result in
  switch result {
  case let .success(presenceSet):
    print("The presence State set as a `JSONCodable`: \(presenceSet)")
  case let .failure(error):
    print("Failed Set State Response: \(error.localizedDescription)")
  }
}

Get State :

pubnub.getPresenceState(
  for: pubnub.configuration.uuid,
  on: ["channelSwift"],
  and: ["demo"]
) { result in
  switch result {
  case let .success(uuid, stateByChannel):
    print("The UUID `\(uuid)` has the following presence state \(stateByChannel)")
  case let .failure(error):
    print("Failed Get State Response: \(error.localizedDescription)")
  }
}

Other Examples

Converting the response to a JSON Dictionary:

pubnub.setPresence(
      state: ["new": "state"],
      on: ["channelSwift"]
    ) { result in
      switch result {
      case let .success(presenceSet):
        print("The String value for `New` is: \(presenceSet.codableValue[rawValue: "New"] as? String)")
      case let .failure(error):
        print("Failed Set State Response: \(error.localizedDescription)")
      }
    }

Converting the response to a custom object:

struct PresenceState: JSONCodable {
    var new: String
  }
  pubnub.setPresence(
    state: ["new": "state"],
    on: ["channelSwift"]
  ) { result in
    switch result {
    case let .success(presenceSet):
      print("The Object representation is: \(try? presenceSet.codableValue.decode(PresenceState.self))")
    case let .failure(error):
      print("Failed Set State Response: \(error.localizedDescription)")
    }
  }