Receiving Firebase Notifications in Foreground but not Background

Question

I've tried everything to get the alerts to pop up while in the background. I receive the data when app is open or while launching. Because I receive the notifications I'm assuming it's in my AppDelegate code or perhaps something wrong in my .plist??? I've followed a few of the standard tutorials on firebase notifications, all this code is from those tutorials.

import UIKit
import CoreData
import Firebase
import UserNotifications
import FirebaseInstanceID
import FirebaseMessaging

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate, MessagingDelegate {
    var window: UIWindow?
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        FirebaseApp.configure()
        if #available(iOS 10.0, *) {
            // For iOS 10 display notification (sent via APNS)
            UNUserNotificationCenter.current().delegate = self
            let authOptions: UNAuthorizationOptions = [.alert, .badge, .sound]
            UNUserNotificationCenter.current().requestAuthorization(
                options: authOptions,
                completionHandler: {_, _ in })
            // For iOS 10 data message (sent via FCM
            Messaging.messaging().delegate = self
        } else {
            let settings: UIUserNotificationSettings =
                UIUserNotificationSettings(types: [.alert, .badge, .sound], categories: nil)
            application.registerUserNotificationSettings(settings)
        }

        application.registerForRemoteNotifications()



        // Override point for customization after application launch.

        NotificationCenter.default.addObserver(self, selector: #selector(self.tokenRefreshNotification(_:)),
                                                         name: NSNotification.Name.InstanceIDTokenRefresh, object: nil)

        return true
    }

    func application(application: UIApplication,
                     didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        Messaging.messaging().apnsToken = deviceToken
    }

    func messaging(_ messaging: Messaging, didRefreshRegistrationToken fcmToken: String) {
        print("refreshed token")
    }

    func applicationWillResignActive(_ application: UIApplication) {
        // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
        // Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
    }

    func applicationDidEnterBackground(_ application: UIApplication) {
        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.

      //  Messaging.messaging().disconnect()
       // print("Disconnected from FCM.")
    }

    func applicationWillEnterForeground(_ application: UIApplication) {
        // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
    }

    func applicationDidBecomeActive(_ application: UIApplication) {
        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
        connectToFcm()
    }

    func applicationWillTerminate(_ application: UIApplication) {
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
        // Saves changes in the application's managed object context before the application terminates.
        self.saveContext()
    }

    // MARK: - Core Data stack

    lazy var persistentContainer: NSPersistentContainer = {
        /*
         The persistent container for the application. This implementation
         creates and returns a container, having loaded the store for the
         application to it. This property is optional since there are legitimate
         error conditions that could cause the creation of the store to fail.
        */
        let container = NSPersistentContainer(name: "firetail")
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.

                /*
                 Typical reasons for an error here include:
                 * The parent directory does not exist, cannot be created, or disallows writing.
                 * The persistent store is not accessible, due to permissions or data protection when the device is locked.
                 * The device is out of space.
                 * The store could not be migrated to the current model version.
                 Check the error message to determine what the actual problem was.
                 */
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
        return container
    }()

    // MARK: - Core Data Saving support

    func saveContext () {
        let context = persistentContainer.viewContext
        if context.hasChanges {
            do {
                try context.save()
            } catch {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                let nserror = error as NSError
                fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
            }
        }
    }
    @objc private func tokenRefreshNotification(_ notification: Notification) {
        if let refreshedToken = InstanceID.instanceID().token() {
            print("InstanceID token: \(refreshedToken)")
        }

        // Connect to FCM since connection may have failed when attempted before having a token.
        connectToFcm()
    }

    func connectToFcm() {
        // Won't connect since there is no token
        guard InstanceID.instanceID().token() != nil else {
            return
        }

        // Disconnect previous FCM connection if it exists.
        Messaging.messaging().disconnect()

        Messaging.messaging().connect { (error) in
            if error != nil {
                print("Unable to connect with FCM. \(error?.localizedDescription ?? "")")
            } else {
                print("Connected to FCM.")
            }
        }
    }

    public func application(received remoteMessage: MessagingRemoteMessage) {

        print(remoteMessage.appData)
    }

}

Answer 1

A few things to note:

1. The simulator cannot receive push notifications.
2. You must have push notifications and background modes (remote notifications & background fetch) enabled in your project's capabilities.

Try adding these lines of code to your app delegate:

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any]) {
        // Will not be called until you open your application from the remote notification (returns to foreground)

        // Note: *with swizzling disabled you must let Messaging know about the message
        // Messaging.messaging().appDidReceiveMessage(userInfo)`

        // Print message ID.
        if let messageId = userInfo["gcm.message_id"] {
            print("Message Id: \(messageId)")
        }

        // Print full message.
        print(userInfo)
        Messaging.messaging().appDidReceiveMessage(userInfo)
    }

    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        // Will not be called until you open your application from the remote notification (returns to foreground)

        // Note: *with swizzling disabled you must let Messaging know about the message
        // Messaging.messaging().appDidReceiveMessage(userInfo)

        // Print message id
        if let messageId = userInfo["gcm.message_id"] {
            print("Message Id: \(messageId)")
        }

        // Print full message.
        print(userInfo)
        Messaging.messaging().appDidReceiveMessage(userInfo)

        completionHandler(UIBackgroundFetchResult.newData)
    }

I also noticed you map your APNS token to Messaging (in didRegisterForRemoteNotificationsWithDeviceToken ) using :

Messaging.messaging().apnsToken = deviceToken

I would try your luck replacing it with the following:

Messaging.messaging().setAPNSToken(deviceToken, type: MessagingAPNSTokenType.sandbox)
        Messaging.messaging().setAPNSToken(deviceToken, type: MessagingAPNSTokenType.prod)

Good luck!

Answer 2

确保通过Firebase以高优先级设置（而不是标准/默认优先级）发送邮件。