在React Native iOS中显示自定义FCM推送通知

#import <Firebase.h>

// ...

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  // ...

  if ([UNUserNotificationCenter class] != nil) {
    [UNUserNotificationCenter currentNotificationCenter].delegate = self;
  }

  [FIRApp configure];

  // ...

  return YES;
}

#import <Firebase.h>
#import <UserNotifications/UserNotifications.h>

// ...

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)notification
                                                       fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
  [[NSNotificationCenter defaultCenter] postNotificationName:FCMNotificationReceived object:self userInfo:notification];
  completionHandler(UIBackgroundFetchResultNoData);
}

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)notification {
  [[NSNotificationCenter defaultCenter] postNotificationName:FCMNotificationReceived object:self userInfo:notification];
}

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
  [FIRMessaging messaging].APNSToken = deviceToken;
}