Skip to main content
  • Core Products
  • Add-Ons
  • Extensions Marketplace
Android
iOS
macOS
Web
Windows
Flutter
Linux C++
Unity

Presence

In Signaling solutions, it is often important to know a user's current online status. For example, in instant messaging, chat applications, and online collaboration tools, users need to see the availability of their contacts. This information is typically displayed as a status message or icon next to a user's name. Presence features in Signaling SDK enable you to monitor join, leave, and status change notifications for users in a channel. Using Presence, you can:

  • Get a list of users currently in a channel and their temporary status data.
  • Get a list of channels a specified user has joined or is subscribed to.
  • Get, set, or remove user statuses.
  • Receive real-time event notifications when users join or leave specified channels.
  • Receive user status change event notifications in real time.

Understand the tech​

Presence provides real-time information about the availability, and the current status of users, for effective communication and collaboration. It enables you to retrieve a list of users in a channel, or to query the list of channels for a specific user. The following figure illustrates how you integrate presence features into your app.

Presence workflow

Prerequisites​

Ensure that you have integrated the Signaling SDK in your project, and implemented the framework functionality from the SDK quickstart page.

Implement presence features​

Using presence, you can implement the following features:

Get channel users​

To obtain a list of online users in a channel, call getOnlineUsers. Depending on your parameter settings, this method returns a list of online user IDs in a channel and their temporary status data, or just the number of online users in the channel. You do not need to join a channel to call this method. This method is applicable to both message channels and stream channels. Use the channelType parameter to specify the channel type.

info

After obtaining the initial online users list, update it in real time through didReceivePresenceEvent event notifications.

Refer to the following sample code to query the list of online users in a channel and their current status:

let presenceOptions = AgoraRtmPresenceOptions()presenceOptions.includeState = truepresenceOptions.includeUserId = true// Retrieve the user state of the current channelrtm.getPresence()?.getOnlineUsers(channelName: "your_channel", channelType: .message, options: presenceOptions) { response, errorInfo in    if errorInfo == nil {        print("getOnlineUsers success!!")        let userCount = response?.totalOccupancy ?? 0        let userStates = response?.userStateList ?? []        // You can process userCount and userStates here    } else {        print("getOnlineUsers failed, errorCode \(errorInfo!.errorCode), reason \(errorInfo!.reason)")    }}
let presenceOptions = AgoraRtmPresenceOptions()presenceOptions.includeState = truepresenceOptions.includeUserId = truepresenceOptions.page = "your_Next_Page_Bookmark"// Retrieve the user state of the current channelrtm.getPresence()?.getOnlineUsers("your_channel", channelType: .message, options: presenceOptions) { response, errorInfo in    if errorInfo == nil {        print("getOnlineUsers success!!")                let userCount = response?.totalOccupancy ?? 0        let nextPage = response?.nextPage ?? ""        let userStates = response?.userStateList ?? []        // You can process userCount, nextPage, and userStates here    } else {        print("getOnlineUsers failed, errorCode \(errorInfo!.errorCode), reason \(errorInfo!.reason)")    }}

When there is a large number of users in a channel, you may only care about the total number of online users, and not their identities or temporary status. To get the total channel occupancy, set includeState and includeUserId in AgoraRtmPresenceOptions to false.

let presenceOptions = AgoraRtmPresenceOptions()presenceOptions.includeState = falsepresenceOptions.includeUserId = false// Retrieve the user state of the current channelrtm.getPresence()?.getOnlineUsers(channelName: "your_channel", channelType: .message, options: presenceOptions) { response, errorInfo in    if errorInfo == nil {        print("getOnlineUsers success!!")                let userCount = response?.totalOccupancy ?? 0    } else {        print("getOnlineUsers failed, errorCode \(errorInfo!.errorCode), reason \(errorInfo!.reason)")    }}

In this case, only the totalOccupancy property in the result is valid while all other fields are empty.

info

You cannot set includeState to true and includeUserId to false at the same time. To get the temporary status of users, you must also retrieve their user IDs.

Get user channels​

The getUserChannels method enables you to query which channels a user is currently in. This includes the message channels a user has subscribed to and the stream channels they have joined. This method is particularly useful for tracking user paths. Refer to the following sample code:

rtm.getPresence()?.getUserChannels("userId") { response, errorInfo in    if errorInfo == nil {        print("getUserChannels success!!")                let channelCount = response?.totalChannel ?? 0        let channels = response?.channels ?? []            } else {        print("getUserChannels failed, errorCode \(errorInfo!.errorCode), reason \(errorInfo!.reason)")    }}

The getUserChannels method returns complete query results about the channels and their types that the queried user is in, without pagination.

User status management​

Signaling enables you to set and delete user status messages for the local user in each channel. The SDK notifies other online users in the channel of these changes through event notifications. This feature is useful in use-cases where user status sharing is required, such as real-time synchronization of the user's microphone status, mood, personal signature, score, and message input status.

Signaling does not permanently save the status data. When a user unsubscribes from a channel, times out, or exits a channel, the data is deleted. To save user data permanently, refer to Store user metadata.

When a user's temporary status changes, Signaling triggers the remote state changed event notification in real-time. Users who enable presence in features when subscribing to a channel, receive the event notification.

Set status​

Using presence, you can set the temporary user status for the local user. When you set the status before subscribing to or joining a channel, the data is cached on the client and does not take effect immediately. The status is updated and corresponding event notifications are triggered when you subscribe to or join a channel. The setState method applies to both message and stream channels; use the channelType parameter to specify the channel type.

let states: [String: String] = ["key1": "value1", "key2": "value2"]rtm.getPresence()?.setState(channelName: "your_channel", channelType: .message, items: states) { response, errorInfo in    if errorInfo == nil {        print("setState success!!")    } else {        print("setState failed, errorCode \(errorInfo!.errorCode), reason \(errorInfo!.reason)")    }}

When using setState to set temporary user status, if the specified key already exists, its value is overwritten by the new value. If the specified key does not exist, a new key-value pair is added.

Get status​

To obtain the temporary user status set by a user in a specified channel, use the getState method:

rtm.getPresence()?.getState(channelName: "Chat_room", channelType: .message, userId: "userid") { response, errorInfo in    if errorInfo == nil {        print("getState success!!")        if let state = response?.state {            // process state        }    } else {        print("getState failed, errorCode \(errorInfo!.errorCode), reason \(errorInfo!.reason)")    }}

If the queried user is not present in the specified channel, a presenceUserNotExist error message is returned by the SDK.

Delete status​

Each user can set up to 32 key-value pairs in a channel. To remove items that are no longer needed, call removeState with a list of keys. The removeState method only deletes temporary user status data for the local user.

let keys: [String] = ["key1", "key2"]rtm.getPresence()?.removeState("your_channel", channelType: .message, keys: keys) { response, errorInfo in    if errorInfo == nil {        print("removeState success!!")    } else {        print("removeState failed, errorCode \(errorInfo!.errorCode), reason \(errorInfo!.reason)")    }}

Both the setState and removeState methods trigger remoteStateChanged event notifications. Users who join the channel with presence enabled in features receive event notifications containing full data of the user's temporary status.

Receive presence event notifications​

A presence event notification returns the AgoraRtmPresenceEvent data structure, which includes the AgoraRtmPresenceEventType parameter.

To receive presence event notifications, implement an event listener. See event listeners for details. In addition, include presence in the features parameter when subscribing to or joining a channel.

Event notification modes​

The presence event notification mode determines how subscribed users receive event notifications. There are two notification modes:

  • Announce: Real-time notification mode
  • Interval: Scheduled notification mode

Set the Max number of instant event value in Agora Console to specify the condition for switching between the two modes. The scheduled notification mode helps prevent event noise that results from a large number of online users in the channel. See Presence configuration for details.

Real-time notification mode​

If the number of instant notifications in the channel is less than the Max number of instant event value, presence event notifications operate in real-time notification mode. In this mode, the following notifications are sent to the client in real-time:

  • remoteJoinChannel
  • remoteLeaveChannel
  • remoteConnectionTimeout
  • remoteStateChanged
{    type: .remoteJoinChannel;    channelType: .message;    channelName: "test_channel";    publisher: "publisher_name";    states: [];    interval: [];    snapshot: [];    timestamp: 1710487149497;}

Scheduled notification mode​

When the number of online users in a channel exceeds the Max number of instant event value, the channel switches to the scheduled notification mode. In this mode, remoteJoinChannel, remoteLeaveChannel, remoteConnectionTimeout, and remoteStateChanged events are replaced by interval events and sent to all users in the channel at specific time intervals. Users receive the following notification:

{      "type": "AgoraRtmPresenceEventTypeInterval",      "channelType": "AgoraRtmChannelTypeMessages",      "channelName": "Chat_room",      "publisher": "Tony",      "interval": {          "remote_join": ["Tony", "Lily"],          "remote_leave": ["Jason"],          "remote_timeout": ["Wendy"],          "remote_state_change": [              {                  "userId": "Harvard",                  "states": [                      { "Mic": "False" },                      { "Position": "Washington" }                  ]              },              {                  "userId": "Harvard",                  "states": [                      { "Mic": "True" },                      { "Position": "Washington" }                  ]              }          ]      }}

Reference​

This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.

API reference​

Page Content

Signaling