Implement silent push notifications
Introduction
Silent push notifications are a special type of remote notification, mainly used for data synchronization between the App running in the background and the server. For example: when the App is not active and the data within the App is outdated, the server will send a silent push notification, and the App will update the data without any user awareness.
Prerequisites
Before implementing silent push notifications, please make sure of the following:
- Implement offline push notifications. For more details, please refer to Implement offline push notification.
Implementation steps
- 
Contact ZEGOCLOUD Technical Support to configure the resourceIDfor carrying silent push strategies.
- 
In scenarios where offline push notifications need to be sent (such as call invitation, offline push notification, etc.), fill in the ZIMPushConfig > resourceID with the pre-configured value obtained from ZEGOCLOUD Technical Support. Additionally, fill in the payload field according to the specific business scenario. 
pushConfig.resourcesID = @"resourcesID configured by ZEGOCLOUD Technical Support";- In the "AppDelegate.m" file, implement the didReceiveRemoteNotificationmethod with your business logic. When the App is in the background and not killed, this method will be triggered. Sample code is as follows:
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
    // Call the completionHandler after the your logic is completed
}- Once the above steps are completed, you can send silent push notifications to others and receive silent push notifications from others.



