code for AppDelegate.m

// Required for the register event.
 - (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken
 {
 [RNCPushNotificationIOS didRegisterForRemoteNotificationsWithDeviceToken:deviceToken];
 }
 // Required for the notification event. You must call the completion handler after handling the remote notification.
 - (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
 fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler
 {
 [RNCPushNotificationIOS didReceiveRemoteNotification:userInfo fetchCompletionHandler:completionHandler];
 }
 // Required for the registrationError event.
 - (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error
 {
 [RNCPushNotificationIOS didFailToRegisterForRemoteNotificationsWithError:error];
 }
 // Required for localNotification event
 - (void)userNotificationCenter:(UNUserNotificationCenter *)center
 didReceiveNotificationResponse:(UNNotificationResponse *)response
 withCompletionHandler:(void (^)(void))completionHandler
 {
 [RNCPushNotificationIOS didReceiveNotificationResponse:response];
 }
 
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
 …
 // Define UNUserNotificationCenter
 UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
 center.delegate = self;
 
 return YES;
 }
 
 //Called when a notification is delivered to a foreground app.
 -(void)userNotificationCenter:(UNUserNotificationCenter *)center willPresentNotification:(UNNotification *)notification withCompletionHandler:(void (^)(UNNotificationPresentationOptions options))completionHandler
 {
 completionHandler(UNNotificationPresentationOptionSound | UNNotificationPresentationOptionAlert | UNNotificationPresentationOptionBadge);
 }