unable to receive the push notification in foreground using FCM

Question

I have been trying to get firebase push-notification in my app. I have tried everything on the internet but couldn't find solution. I have been receiving notification in background, but when App is in foreground I am unable to get the notification. But when I print the userInfo in "didReceiveRemoteNotification" I get the message in console Any help would be appreciated.

import Firebase
import UserNotifications


@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate{

var window: UIWindow?


func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

    //FirebaseApp.configure()

    self.initializeFCM(application)
    let token = InstanceID.instanceID().token()
    debugPrint("GCM TOKEN = \(String(describing: token))")

    return true
}

 func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error)
{
    debugPrint("didFailToRegisterForRemoteNotificationsWithError: \(error)")
}

func application(received remoteMessage: MessagingRemoteMessage)
{
    debugPrint("remoteMessage:\(remoteMessage.appData)")
}

func initializeFCM(_ application: UIApplication)
{
    print("initializeFCM")

    if #available(iOS 10.0, *) // enable new way for notifications on iOS 10
    {
        let center = UNUserNotificationCenter.current()
        center.delegate = self
        center.requestAuthorization(options: [.badge, .alert , .sound]) { (accepted, error) in
            if !accepted
            {
                print("Notification access denied.")
            }
            else
            {
                print("Notification access accepted.")
                UIApplication.shared.registerForRemoteNotifications();
            }
        }
    }
    else
    {
        let type: UIUserNotificationType = [UIUserNotificationType.badge, UIUserNotificationType.alert, UIUserNotificationType.sound];
        let setting = UIUserNotificationSettings(types: type, categories: nil);
        UIApplication.shared.registerUserNotificationSettings(setting);
        UIApplication.shared.registerForRemoteNotifications();
    }

    FirebaseApp.configure()
    Messaging.messaging().delegate = self
    Messaging.messaging().shouldEstablishDirectChannel = true

}

// enable new way for notifications on iOS 10

func application(_ application: UIApplication, didRegister notificationSettings: UIUserNotificationSettings)
{
    debugPrint("didRegister notificationSettings")
    if (notificationSettings.types == .alert || notificationSettings.types == .badge || notificationSettings.types == .sound)
    {
        application.registerForRemoteNotifications()
    }
}


func application(application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData)
{
    debugPrint("didRegisterForRemoteNotificationsWithDeviceToken: NSDATA")

    let token = String(format: "%@", deviceToken as CVarArg)
    debugPrint("*** deviceToken: \(token)")

    Messaging.messaging().apnsToken = deviceToken as Data
    debugPrint("Firebase Token:",InstanceID.instanceID().token() as Any)
}

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data)
{
    debugPrint("didRegisterForRemoteNotificationsWithDeviceToken: DATA")
    let token = String(format: "%@", deviceToken as CVarArg)
    debugPrint("*** deviceToken: \(token)")

    Messaging.messaging().apnsToken = deviceToken
    debugPrint("Firebase Token:",InstanceID.instanceID().token() as Any)
}
//-------------------------------------------------------------------------//

// [START receive_message]
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any]) {

    Messaging.messaging().appDidReceiveMessage(userInfo)
    print(userInfo)
}

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any],
                 fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
    Messaging.messaging().appDidReceiveMessage(userInfo)
    print(userInfo)

    completionHandler(UIBackgroundFetchResult.newData)
}
// [END receive_message]

}


// [START ios_10_message_handling]
@available(iOS 10, *)
extension AppDelegate : UNUserNotificationCenterDelegate {

// Receive displayed notifications for iOS 10 devices.
func userNotificationCenter(_ center: UNUserNotificationCenter,
                            willPresent notification: UNNotification,
                            withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
    let userInfo = notification.request.content.userInfo

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

    // Change this to your preferred presentation option
    completionHandler([])
}

func userNotificationCenter(_ center: UNUserNotificationCenter,
                            didReceive response: UNNotificationResponse,
                            withCompletionHandler completionHandler: @escaping () -> Void) {
    let userInfo = response.notification.request.content.userInfo
    Messaging.messaging().appDidReceiveMessage(userInfo)
    print(userInfo)

    completionHandler()
 }
}
 // [END ios_10_message_handling]

 extension AppDelegate : MessagingDelegate {
// [START refresh_token]
 func messaging(_ messaging: Messaging, didRefreshRegistrationToken fcmToken: String) {
    print("Firebase registration token: \(fcmToken)")
}

func messaging(_ messaging: Messaging, didReceive remoteMessage: MessagingRemoteMessage) {
    print("Received data message: \(remoteMessage.appData)")
}
// [END ios_10_data_message]
}

Answer 1

Since iOS 14, .alert is deprecated, you might use .banner instead:

func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
    let content = notification.request.content
    // Process notification content
    print("\(content.userInfo)")
    completionHandler([.banner, .list, .sound]) // Display notification Banner     
}

---

From iOS 10, You can display Apple's default notification banner using below function. Notification behaviour will depend on properties which you return within completionHandler.

func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
    let content = notification.request.content
    // Process notification content
    print("\(content.userInfo)")
    completionHandler([.alert, .sound]) // Display notification Banner
}

As per details in your question, you have already implemented above function, but with blank completionHandler(). Because of that notification banner doesn't display while app is in foreground state.

Earlier iOS 10:

You need to handle this by yourself. Like if you want to display banner when you received a notification, while app is in foreground state. You need to do this by yourself. You have to design your custom notification banner to display within app.

Hope it helps you.

Answer 2

1. Add this func in your AppDelegate:

   func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
       completionHandler([.alert, .sound, .badge])
   }
   

2. Add UNUserNotificationCenterDelegate protocol to your AppDelegate class like this:

   class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate { 
   

3. Add below line in didFinishLaunchingWithOptions func:

   UNUserNotificationCenter.current().delegate = self