Firebase Messaging shouldEstablishDirectChannel 未在首次应用启动时建立连接

Question

问题

第一次启动应用程序时，或删除并重新安装后，Messaging.messaging().shouldEstablishDirectChannel 不会建立套接字连接。如果我关闭了应用程序，然后重新打开它，那么套接字连接就建立了。

重现步骤：

1) 将此代码放在 AppDelegate 中： FirebaseApp.configure() Messaging.messaging().delegate = self Messaging.messaging().shouldEstablishDirectChannel = true

2) 将此代码放在后面的任何位置，以检查是否建立了连接： Messaging.messaging().isDirectChannelEstablished 这总是返回 false。

3) 监听连接状态变化并观察此通知永远不会被触发。 NotificationCenter.default.addObserver(self, selector: #selector(fcmConnectionStateChange), name: NSNotification.Name.MessagingConnectionStateChanged, object: nil)

简而言之，这就是问题所在。如果我只是杀死应用程序，然后重新启动它，一切都会按预期工作。建立套接字连接并触发MessagingConnectionStateChanged 通知。

为什么Messaging.messaging().shouldEstablishDirectChannel 在我的首次应用启动时没有连接？

相关代码

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        window = UIWindow(frame: UIScreen.main.bounds)
        window!.rootViewController = RootViewController.shared
        window!.makeKeyAndVisible()
        setUpFirebase()
        setUpPushNotificationsForApplication(application)
        RootViewController.shared.goToLoginVC()

        return true
    }

    // MARK: - Firebase

    func setUpFirebase() {
        NotificationCenter.default.addObserver(self, selector:
            #selector(fcmConnectionStateChange), name:
            NSNotification.Name.MessagingConnectionStateChanged, object: nil)        
        FirebaseApp.configure()
        Messaging.messaging().delegate = self
        Messaging.messaging().shouldEstablishDirectChannel = true
    }

    // MARK: - Firebase Notifications

    func fcmConnectionStateChange() {
       // This is never called on app's first launch!!!
        print(Messaging.messaging().isDirectChannelEstablished)
    }

环境

• Xcode 版本：8.3.3
• Firebase 4.1.0
• FirebaseAnalytics 4.0.3
• FirebaseCore 4.0.5
• FirebaseInstanceID 2.0.1
• FirebaseMessaging 2.0.1
• Firebase 产品：消息传递

Answer 1

在获得令牌之前尝试 FCM 连接可能失败。

我修改了你的代码，试试这个。

func setUpFirebase() {
    NotificationCenter.default.addObserver(self, selector: 
        #selector(self.tokenRefreshNotification), name: 
        NSNotification.Name.InstanceIDTokenRefresh, object: nil)
    NotificationCenter.default.addObserver(self, selector:
        #selector(self.fcmConnectionStateChange), name:
        NSNotification.Name.MessagingConnectionStateChanged, object: nil)        
    FirebaseApp.configure()
    Messaging.messaging().delegate = self
}

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;
    }
    Messaging.messaging().shouldEstablishDirectChannel = true
}

func fcmConnectionStateChange() {
    if Messaging.messaging().isDirectChannelEstablished {
        print("Connected to FCM.")
    } else {
        print("Disconnected from FCM.")
    }
}

更新： 在使用 NotificationCenter 之前添加它。

    if #available(iOS 10, *) {
        print("iOS 10 up")
        let center = UNUserNotificationCenter.current()
        center.requestAuthorization(options: [.alert, .badge, .sound]) { (granted, error) in
            guard error == nil else {
                print("regist fail = \(String(describing: error))")
                return
            }
            if granted {
                print("allow regist")
            } else {
                //Handle user denying permissions..
                print("deny regist")
            }
        }
    } else {
        print("iOS 9 down")
        let pushNotificationSettings = UIUserNotificationSettings(types: [.alert, .badge, .sound], categories: nil)
        application.registerUserNotificationSettings( pushNotificationSettings )
    }
    application.registerForRemoteNotifications()