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@Override public void onMessageReceived(RemoteMessage remoteMessage) { // ... // TODO(developer): Handle FCM messages here. Log.d(TAG, "From: " + remoteMessage.getFrom()); // Check if message contains a data payload. if (remoteMessage.getData().size() > 0) ...

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler { // If you are receiving a notification message while your app is in the background, // this callback will no...

Firebase handles notifications differently when the app is in background (killed process) and when in foreground (active). When your app is in the background, notification messages are displayed in the system tray, and onMessageReceived is not called. For notification messages with a data payload...