Push Notifications are delivered but didReceiveRemoteNotification is never called Swift

Question

I have successfully implemented push notifications in my two related apps via FCM and while trying to implement some logic to increment badge number on receiving the notification.

I realized that didReceiveRemoteNotificationdelegate method is not called at all as I don't get any prints out of it, but I do get prints from willPresent notificationand didReceive response. So setting UIApplication.shared.applicationIconBadgeNumber in didFinishLaunchingWithOptionshas no effect, but setting in it didReceive responsedoes.

Following the documentation didReceiveRemoteNotification should be called but I never get prints out of it when a notification arrives.

I tried commenting out the whole didReceiveRemoteNotificationmethod and notifications are still delivered.

Why is it so? I guess I didn't really understand who's handling messaging in this set up. Can you please help me clarifying it?

AppDelegate methods:

didFinishLaunchingWithOptions:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        window?.tintColor = UIColor.blue
        // Use Firebase library to configure APIs
        FirebaseApp.configure()
        Messaging.messaging().delegate = self
        Crashlytics().debugMode = true
        Fabric.with([Crashlytics.self])
        // setting up notification delegate
        if #available(iOS 10.0, *) {
            //iOS 10.0 and greater
            UNUserNotificationCenter.current().delegate = self
            let authOptions: UNAuthorizationOptions = [.alert, .badge, .sound]
            //Solicit permission from the user to receive notifications
            UNUserNotificationCenter.current().requestAuthorization(options: authOptions, completionHandler: { granted, error in
                DispatchQueue.main.async {
                    if granted {
                        print("didFinishLaunchingWithOptions iOS 10: Successfully registered for APNs")
                        UIApplication.shared.registerForRemoteNotifications()
//                        UIApplication.shared.applicationIconBadgeNumber = 1
                        AppDelegate.badgeCountNumber = 0
                        UIApplication.shared.applicationIconBadgeNumber = 0
                    } else {
                        //Do stuff if unsuccessful...
                        print("didFinishLaunchingWithOptions iOO 10: Error in registering for APNs: \(String(describing: error))")
                    }
                }
            })
        } else {
            //iOS 9
            let type: UIUserNotificationType = [UIUserNotificationType.badge, UIUserNotificationType.alert, UIUserNotificationType.sound]
            let setting = UIUserNotificationSettings(types: type, categories: nil)
            UIApplication.shared.registerUserNotificationSettings(setting)
            UIApplication.shared.registerForRemoteNotifications()
//            UIApplication.shared.applicationIconBadgeNumber = 1
            UIApplication.shared.applicationIconBadgeNumber = 0
            print("didFinishLaunchingWithOptions iOS 9: Successfully registered for APNs")
        }
        // setting up remote control values
        let _ = RCValues.sharedInstance
        GIDSignIn.sharedInstance().clientID = FirebaseApp.app()?.options.clientID
        Crashlytics().debugMode = true
        Fabric.with([Crashlytics.self])
        //        // TODO: Move this to where you establish a user session
        //        self.logUser()
        var error: NSError?
        do {
            try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
        } catch let error1 as NSError{
            error = error1
            print("could not set session. err:\(error!.localizedDescription)")
        }
        do {
            try AVAudioSession.sharedInstance().setActive(true)
        } catch let error1 as NSError{
            error = error1
            print("could not active session. err:\(error!.localizedDescription)")
        }
        // goggle only
        GIDSignIn.sharedInstance().clientID = FirebaseApp.app()?.options.clientID
//        GIDSignIn.sharedInstance().delegate = self
        // Facebook SDK
        return FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)
//        return true
    }

didReceiveRemoteNotification:

 // foreground
        func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any]) {
            print("didReceiveRemoteNotification: Received new push Notification")
            // 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)
            AppDelegate.badgeCountNumber += userInfo["badge"] as! Int
            print("AppDelegate.badgeCountNumber is : \(String(describing: AppDelegate.badgeCountNumber))")
//            UIApplication.shared.applicationIconBadgeNumber = AppDelegate.badgeCountNumber
            UIApplication.shared.applicationIconBadgeNumber =  10//AppDelegate.badgeCountNumber
            // Print full message.
            print("didReceiveRemoteNotification: Push notificationMessage is: \(userInfo)")
        }




        // background
    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any],
                     fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        print("didReceiveRemoteNotification with handler : Received new push Notification while in background")
        // 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)
        if let messageID = userInfo[ userDetails.fcmToken] { // working for looged in
            print("didReceiveRemoteNotification: Message ID: \(messageID)")
        }

        // Print full message.
        print("didReceiveRemoteNotification: Push notificationMessage is: \(userInfo)")
        AppDelegate.badgeCountNumber += userInfo["badge"] as! Int
        print("AppDelegate.badgeCountNumber is : \(String(describing: AppDelegate.badgeCountNumber))")
        UIApplication.shared.applicationIconBadgeNumber +=  userInfo["badge"] as! Int
        completionHandler(UIBackgroundFetchResult.newData)
    }

Answer 1

I finally found the solution. Alert needs"content_available": true to be set in the alert definition from the post sending funtion from App2 to App1 or else notifications get delivered but 'didReceiveRemoteNotification` is not called and you can't use 'userInfo'. Hope this will help others as I haven't found much info about this problem. If you're setting the notification with Postman or similars check here didReceiveRemoteNotification function doesn't called with FCM notification server as that's the only post I found on this problem and solved mine. Thanks to @Ranjani for trying helping me.

let postParams: [String : Any] = [
                "to": receiverToken,
                "notification": [
                    "badge" : 1,
                    "body": body,
                    "title": title,
                    "subtitle": subtitle,
                    "sound" : true, // or specify audio name to play
                    "content_available": true, // this will call didReceiveRemoteNotification in receiving app, else won't work
                    "priority": "high"
                ],
                "data" : [
                    "data": "ciao",
            ]
                ]

Answer 2

For Node.js (send to topic example)

var admin = require("firebase-admin");

var serviceAccount = require("path/to/serviceAccountKey.json");

admin.initializeApp({
    credential: admin.credential.cert(serviceAccount),
    databaseURL: "<your database URL>"
});

var topic = "topicA";

var payload = {
    notification: {
        title: "title",
        body: "body",
        sound: "default"
    },
    data: {
        a: "dataA",
        b: "dataB"
    }
};

var options = {
    content_available: true,
    priority: "high",
    timeToLive: 1
};

// Send a message to devices subscribed to the provided topic.
admin.messaging().sendToTopic(topic, payload, options)
    .then((response) => {
        // Response is a message ID string.
        console.log('Successfully sent message:', response);
    })
    .catch((error) => {
        console.log('Error sending message:', error);
    });