SyncManager SDKs iOS v1
SyncManager SDKs iOS
SyncManager SDKs
Version 1

Install SyncManager

Copy link

This page provides a guide that demonstrates how to integrate Sendbird SyncManager onto a client app. Sendbird SyncManager can be installed through CocoaPods or Carthage. Start building the add-on to your Chat SDK by clicking the Download SyncManager button below.

Note: Sendbird Chat SDK is required in order to use Sendbird SyncManager because it is an add-on feature.

Download SyncManager

Copy link

Download SyncManager

Install SyncManager

Copy link

SyncManager for iOS can be installed in two ways: via CocoaPods or Carthage.


Copy link

Add SendBirdSyncManager into your Podfile in Xcode as below:

platform :ios, '8.0'

    pod 'SendBirdSyncManager'

Install the Sendbird SyncManager framework through CocoaPods.

$ pod install

Update the Sendbird SyncManager framework through CocoaPods.

$ pod update SendBirdSyncManager

Note: SendBirdSyncManager is Sendbird Chat SDK-dependent. If you install SendBirdSyncManager, CocoaPods will automatically install the Chat SDK for iOS as well. The minimum required version of Sendbird Chat SDK for iOS is 3.0.155 or later.


Copy link

Add SendBirdSyncManager into your Cartfile in Xcode as below:

github "sendbird/sendbird-syncmanager-ios"

Install the Sendbird SyncManager framework through Carthage as below:

carthage update

Go to your Xcode project's General settings tab. Then, open <YOUR_XCODE_PROJECT_DIRECTORY>/Carthage/Build/iOS in the Finder window and drag SendBirdSyncManager.framework to the Embedded Binaries section in Xcode. Make sure Copy items if needed is checked and click Finish.

How it works

Copy link

SyncManager is designed to simplify the process of integrating chat in your iOS client app by leveraging local caching. While Sendbird Chat SDK for iOS is highly customizable with a number of atomic features, SyncManager facilitates SDK integration by managing most background operations needed to run chat in your iOS client app.

Event-driven structure

Copy link

SyncManager has an event-driven architecture that updates the chatting view based on data events. Events received through the WebSocket connection as well as processed data in the cache are delivered to the client app by the SyncManager’s collection delegates and can be leveraged when implementing your view.


Copy link

As a key component that can be used for view implementation, the Collection holds items that comprise channel or message data. In your view, a collection instance can be binded to an event delegate to subscribe to events. In the callbacks of the event delegate, you can implement what jobs to execute when a specific type of event happens. The following shows a simple example of how you can create a channel collection and bind it to a collection event handler:

SBDGroupChannelListQuery *listQuery = [SBDGroupChannel createMyGroupChannelListQuery];
SBSMChannelCollection *channelCollection = [SBSMChannelCollection collectionWithQuery:listQuery];
channelCollection.delegate = self;

// Channel collection delegate
- (void)collection:(SBSMChannelCollection *)collection didReceiveEvent:(SBSMChannelEventAction)action channels:(NSArray<SBDGroupChannel *> *)channels {
    switch (action) {
            case SBSMChannelEventActionInsert: {
            // Insert channels on the list.
        case SBSMChannelEventActionUpdate: {
            // Update channels on the list.
        case SBSMChannelEventActionRemove: {
            // Remove channels on the list.
        case SBSMChannelEventActionMove: {
            // Move channels on the list.
        case SBSMChannelEventActionClear: {
            // Clear all channels.
        case SBSMChannelEventActionNone:
        default: {

Background sync

Copy link

Background sync is a feature of SyncManager that automatically stores data fetched from Sendbird server in the local cache. When a collection is created, the background sync process starts running with the given conditions. Background sync should follow the lifecycle of a connection: the pauseSynchronize method is called when a connection is lost and the resumeSynchronize method is called when a connection is established.

For example, even if only 2 out of 12 channels are cached, background sync feeds the uncached Sendbird server data to the chatting view so that all 12 channels are displayed. In order for this to happen, the channel collection’s fetch method should be called, and the collection brings the insert event for the two channels from the cache. Then, the uncached 10 channels are synchronized through background sync. After synchronization is completed, another insert event is given for the uncached 10 channels. Through this process, all 12 channels are displayed in the view.

Real-time event sync

Copy link

Real-time event sync is a feature of SyncManager that listens for real-time events received through the WebSocket connection. When an event arrives, SyncManager identifies it, stores it in the cache, and delivers it to the collection handler with the appropriate action such as insert or remove.

Offline mode

Copy link

SyncManager ensures your client app is operational during offline mode. If background sync isn’t running because a connection with the server hasn’t been established, the view can display cached data provided by SyncManager. Once a connection is re-established, the resumeSynchronize method resumes background sync for data synchronization.

Implementation guide

Copy link

This section describes how to implement SyncManager in your iOS client app.


Copy link

Initialize and set up the database for SyncManager as below:

SBSMSyncManagerOptions *options = [SBSMSyncManagerOptions options];
options.messageCollectionCapacity = 200;
options.messageResendPolicy = SBSMMessageResendPolicyManual;
options.maxFailedMessageCountPerChannel = 5;
[SBSMSyncManager setupWithUserId:connector.userId options:options];

SyncManager database

Copy link



Specifies the ID of the user.



Specifies the options for how SyncManager works.

The SBSMSyncManagerOptions has the following properties:

List of properties

Copy link
Property nameDescription


Determines the maximum capacity of messages in a collection related to a chat view. Messages that exceed the maximum capacity are removed. Acceptable values are from 200 to 2,147,483,647. (Default: 2,147,483,647)


Determines the policy for handling failed messages. If delivery of a message fails, SyncManager performs different actions based on the configured policy. Acceptable values are:
- none (default): removes the pending message.
- manual: stores the failed message in the local cache and updates the pending message state as failed.
- automatic: performs the same actions as manual, but also tries to automatically resend the failed message.


Determines the maximum number of attempts to resend a failed message. Resend attempts are stopped for messages that have been resent the maximum number of attempts and they remain as failed. The messageResendPolicy value must be set as automatic for this to be applicable. (Default: 2,147,483,647)


Determines the maximum number of failed messages allowed in a channel. SyncManager deletes the earliest failed message and delivers the remove event through the SBSMMessageCollectionDelegate if the number of failed messages exceeds this limit. (Default: 20)


Determines the number of days to retain failed messages. Once failed messages have been retained for the retention period, they are automatically removed. (Default: 7)

Connection handling

Copy link

When the Chat SDK is connected to Sendbird server, SyncManager fetches the current user’s chat-related data from the server to update the local cache. This enables SyncManager to synchronize the local cache with the channel and message data.

Additional jobs, which detect changes in connection status and notify SyncManager, are needed when data is fetched from the server through the Chat SDK’s connection delegate: the resumeSynchronize and pauseSynchronize methods. The resumeSynchronize should be called in the didSucceedReconnection to run background processes for data synchronization when connected, whereas the pauseSynchronize should be called in the didStartReconnection to pause the background processes when disconnected.

[SBDMain addConnectionDelegate:self identifier:self.description];

// Connection delegates
- (void)didStartReconnection {
    [SBSMSyncManager pauseSynchronize];
- (void)didSucceedReconnection {
    [SBSMSyncManager resumeSynchronize];
- (void)didFailReconnection {
- (void)didCancelReconnection {

Note: The SBDMain removeAllConnectionDelegate or SBDMain removeAllChannelDelegate method shouldn’t be called because they remove not only the delegates you’ve added, but also the other delegates internally managed by SyncManager.

Clear local cache

Copy link

The cache can be cleared regardless of connection to Sendbird server using the clearCache method.

[SBSMSyncManager clearCache];

Note: The clearCache is designed for debugging purposes only. Using it for other purposes isn’t recommended.