Events overview

The OpenIM iOS SDK defines listener protocols by domain. Add and remove listeners through [OIMManager callbacker], and keep a strong reference to each listener in your application state layer because the callbacker holds weak references to them.

Registration lifecycle

Register application-level listeners after initSDK succeeds and before login. Do not add them again every time a view renders or appears. When the user logs out or switches accounts, or when the state layer is destroyed, call the corresponding remove...Listener: method with the same instance.

Conversation groups are an exception. OpenIMCore uses Open_im_sdkSetConversationGroupListener to set a single Open_im_sdk_callbackOnConversationGroupListener. It does not go through [OIMManager callbacker] and is not an OIMCallbacker listener that can be added repeatedly. The conversation state layer should retain this callback object for the SDK lifecycle and set it only once. For the complete callback and JSON payloads, see Conversation groups overview.

Listen for initial synchronization

The synchronization lifecycle belongs to OIMConversationListener. This page is the canonical implementation page for its four synchronization callbacks:

@interface SDKSyncStore () <OIMConversationListener>
@end

@implementation SDKSyncStore

- (void)startListening {
    [[OIMManager callbacker] addConversationListener:self];
}

- (void)stopListening {
    [[OIMManager callbacker] removeConversationListener:self];
}

- (void)onSyncServerStart:(BOOL)reInstall {
    [self setSyncingWithProgress:0 reInstall:reInstall];
}

- (void)onSyncServerProgress:(NSInteger)progress {
    [self setSyncingWithProgress:progress reInstall:self.reInstallSync];
}

- (void)onSyncServerFinish:(BOOL)reInstall {
    [self setSyncReadyWithReInstall:reInstall];
    [self reloadVisibleSnapshots];
}

- (void)onSyncServerFailed:(BOOL)reInstall {
    [self setSyncFailedWithReInstall:reInstall];
}

@end

When reInstall is YES, synchronization follows a local database rebuild and generally requires a more comprehensive loading state. onSyncServerProgress: reports the current progress. After synchronization finishes, query the snapshots needed by the current UI again, then continue merging subsequent increments from each domain listener.

A synchronization event is not the success callback of a query API and has no business-entity merge key. Handle synchronization completion, snapshot queries, and subsequent event increments as separate stages. Isolate their state by the current SDK instance and logged-in user.