Messaging didReceiveRegistrationToken called twice on startup after deleting and reinstalling app

[petkotodorov]

[REQUIRED] Step 1: Describe your environment

• Xcode version: 12.0.1
• Firebase SDK version: 6.34.0
• Firebase Component: Messaging
• Component version: 4.7.1
• Installation method: CocoaPods

[REQUIRED] Step 2: Describe the problem

didReceiveRegistrationToken is being called twice on first start after deleting and installing app. In that case, app is not receiving notifications. It is not happening, when this is first ever install on the particular device.

Steps to reproduce:

1. Run app for the very first time on this device and didReceiveRegistrationToken is called once with token (as expected)
2. Delete app.
3. Run app, freshly installed again and this time didReceiveRegistrationToken is called twice. First time with the token from previous installation. And a second later, didReceiveRegistrationToken called again with new token.
4. In result is that, during that run app is not receiving notifications
5. On each next run, didReceiveRegistrationToken is called once and all is good

If you have a downloadable sample project that reproduces the bug you're reporting, you will
likely receive a faster response on your issue.

Relevant Code:

func application(_ application: UIApplication, didFinishLaunchingWithOptions _: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        FirebaseApp.configure()
        
        Messaging.messaging().delegate = self
        UNUserNotificationCenter.current().delegate = self
        let authOptions: UNAuthorizationOptions = [.alert, .badge, .sound]
        UNUserNotificationCenter.current().requestAuthorization(
            options: authOptions,
            completionHandler: {_, _ in })
        application.registerForRemoteNotifications()
        return true
    }

 extension AppDelegate: UNUserNotificationCenterDelegate {
    
    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any],
                     fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        // With swizzling disabled you must let Messaging know about the message, for Analytics
        //Messaging.messaging().appDidReceiveMessage(userInfo)

        // Print full message.
        print("did receive RN: \(userInfo)")

        completionHandler(UIBackgroundFetchResult.newData)
    }
}

extension AppDelegate: MessagingDelegate {
    
    func messaging(_ messaging: Messaging, didReceiveRegistrationToken fcmToken: String) {
        print("Firebase registration token from message delegate: \(String(describing: fcmToken))")

//        let dataDict:[String: String] = ["token": fcmToken ?? ""]
//        NotificationCenter.default.post(name: Notification.Name("FCMToken"), object: nil, userInfo: dataDict)
        // TODO: If necessary send token to application server.
        // Note: This callback is fired at each app startup and whenever a new token is generated.
    }
    
}

[morganchen12]

Can you share the Firebase/Messaging logs from your app launch?

[petkotodorov]

@morganchen12 Of, course. Here's everything Firebase related (Analytics, Crashlytics, Messaging)

2020-10-23 10:41:39.221165-0700 ***-mwallet-ios[3562:1545878] 6.34.0 - [Firebase/Analytics][I-ACS023007] Analytics v.60900000 started
2020-10-23 10:41:39.221586-0700 ***-mwallet-ios[3562:1545878] 6.34.0 - [Firebase/Analytics][I-ACS023008] To enable debug logging set the following application argument: -FIRAnalyticsDebugEnabled (see http://goo.gl/RfcP7r)
2020-10-23 10:41:39.229901-0700 ***-mwallet-ios[3562:1545881] 6.34.0 - [Firebase/Messaging][I-FCM001000] FIRMessaging Remote Notifications proxy enabled, will swizzle remote notification receiver handlers. If you'd prefer to manually integrate Firebase Messaging, add "FirebaseAppDelegateProxyEnabled" to your Info.plist, and set it to NO. Follow the instructions at:
https://firebase.google.com/docs/cloud-messaging/ios/client#method_swizzling_in_firebase_messaging
to ensure proper integration.
2020-10-23 10:41:39.230738-0700 ***-mwallet-ios[3562:1545647] [Firebase/Crashlytics] Version 4.6.2
2020-10-23 10:41:39.394452-0700 ***-mwallet-ios[3562:1545876] 6.34.0 - [Firebase/Analytics][I-ACS800023] No pending snapshot to activate. SDK name: app_measurement
2020-10-23 10:41:39.472991-0700 ***-mwallet-ios[3562:1545873] 6.34.0 - [Firebase/Analytics][I-ACS023012] Analytics collection enabled
2020-10-23 10:41:39.473136-0700 ***-mwallet-ios[3562:1545873] 6.34.0 - [Firebase/Analytics][I-ACS023220] Analytics screen reporting is enabled. Call +[FIRAnalytics logEventWithName:FIREventScreenView parameters:] to log a screen view event. To disable automatic screen reporting, set the flag FirebaseAutomaticScreenReportingEnabled to NO (boolean) in the Info.plist

[charlotteliang]

Can you share all Firebase debug Logs when you reproduce?

Here's how you can get the debug logs: To enable debug logging set the following application argument: -FIRDebugEnabled (see http://goo.gl/RfcP7r)

[petkotodorov]

@chliangGoogle Here you go.. I created a gist, as it was rather long. Can paste it here also, if you need.
https://gist.github.com/petkotodorov/44855167a90c310c61857b7a76ab756c

[Xedart]

Same issue for me

[charlotteliang]

Hi @petkotodorov This is expected. We recently discover that sometimes, the APNS token is collected from Apple with a slight delay after first token request was issued, so client has to issue a second token request with the apns token mapping in it. So you are getting that scenario which is why you are getting the token callback twice.

It wasn't happening before because there was a bug that the second token request is not triggered and was recently fixed in #6669.

This should not affect your work as long as you always keep your token updated with the Messaging didReceiveRegistrationToken: callback.