Receive Messages in an iOS App

Once your client app is installed on a device, it can receive messages through the FCM APNs interface. You can immediately start sending notifications to user segments with the Notifications composer, or your application server can send messages with a notification payload through the APNs interface.

Handling messages received through the FCM APNs interface is likely to cover most typical use cases. You can also send upstream messages, or receive data messages in foregrounded apps.

Handle messages received through the FCM APNs interface

When your app is in the background, iOS directs messages with the notification key to the system tray. A tap on a notification opens the app, and the content of the notification is passed to the didReceiveRemoteNotification callback in the AppDelegate.

Implement AppDelegate application:didReceiveRemoteNotification: as shown:

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any]) {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // Messaging.messaging().appDidReceiveMessage(userInfo)

  // Print message ID.
  if let messageID = userInfo[gcmMessageIDKey] {
    print("Message ID: \(messageID)")
  }

  // Print full message.
  print(userInfo)
}

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any],
                 fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // Messaging.messaging().appDidReceiveMessage(userInfo)

  // Print message ID.
  if let messageID = userInfo[gcmMessageIDKey] {
    print("Message ID: \(messageID)")
  }

  // Print full message.
  print(userInfo)

  completionHandler(UIBackgroundFetchResult.newData)
}
AppDelegate.swift

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // [[Messaging messaging] appDidReceiveMessage:userInfo];

  // Print message ID.
  if (userInfo[kGCMMessageIDKey]) {
    NSLog(@"Message ID: %@", userInfo[kGCMMessageIDKey]);
  }

  // Print full message.
  NSLog(@"%@", userInfo);
}

- (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 not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // [[Messaging messaging] appDidReceiveMessage:userInfo];

  // Print message ID.
  if (userInfo[kGCMMessageIDKey]) {
    NSLog(@"Message ID: %@", userInfo[kGCMMessageIDKey]);
  }

  // Print full message.
  NSLog(@"%@", userInfo);

  completionHandler(UIBackgroundFetchResultNewData);
}
AppDelegate.m

If you want to open your app and perform a specific action, set click_action in the notification payload. Use the value that you would use for the category key in the APNs payload.

Interpreting notification message payload

The payload of both notification messages is a dictionary of keys and values. Notification messages sent through APNs follow the APNs payload format as below:

  {
    "aps" : {
      "alert" : {
        "body" : "great match!",
        "title" : "Portugal vs. Denmark",
      },
      "badge" : 1,
    },
    "customKey" : "customValue"
  }

Handle data messages in foregrounded apps

To connect, set the shouldEstablishDirectChannel flag to YES in the AppDelegate. FCM manages the connection, closing it when your app goes into the background and reopening it whenever the app is foregrounded.

Handle messages with method swizzling disabled

If you disable method swizzling, you'll need to call method appDidReceiveMessage:. This lets FCM track message delivery and analytics, which is performed automatically with method swizzling enabled.

// With "FirebaseAppDelegateProxyEnabled": NO
   - (void)application:(UIApplication *)application
     didReceiveRemoteNotification:(NSDictionary *)userInfo
           fetchCompletionHandler:
               (void (^)(UIBackgroundFetchResult))completionHandler {
   // Let FCM know about the message for analytics etc.
   [[FIRMessaging messaging] appDidReceiveMessage:userInfo];
   // handle your message.
 }
 

func application(application: UIApplication, didReceiveRemoteNotification userInfo: [NSObject : AnyObject], fetchCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void) {
     // Let FCM know about the message for analytics etc.
     FIRMessaging.messaging().appDidReceiveMessage(userInfo)
     // handle your message
   }
 

Interpreting data message payload

The payload of data messages is a dictionary of keys and values. Data messages sent to the devices directly by FCM server are expressed in the format of a dictionary as below：

  {
    "body" : "great match!",
    "title" : "Portugal vs. Denmark",
    "icon" : "myicon"
  }