iOS FCM通知无法在后台运行

我正在Swift中开发一个必须使用FCM作为通知服务的应用程序 . 在我的应用程序中，FCM仅在前景而非后台时才起作用 .

我已经尝试了几种方法，例如：

• 禁用和启用调配方法

• 设置 priority 至 high

• 在我的有效载荷中将 data 更改为 notification

我也有一个错误：

Failed to fetch APNS token Error Domain=com.firebase.iid Code=1001 "(null)"

但通知在前台工作没有任何问题 . 以下是我的AppDelegate：

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

        FIRApp.configure()

        // Add observer for InstanceID token refresh callback.
        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(self.tokenRefreshNotification),
                                                         name: kFIRInstanceIDTokenRefreshNotification, object: nil)

        return true
    }

    func registerForPushNotifications(application: UIApplication) {
        let notificationSettings = UIUserNotificationSettings(
            forTypes: [.Badge, .Sound, .Alert], categories: nil)
        application.registerUserNotificationSettings(notificationSettings)
    }

    func application(application: UIApplication, didRegisterUserNotificationSettings notificationSettings: UIUserNotificationSettings) {
        if notificationSettings.types != .None {
            application.registerForRemoteNotifications()
        }
    }

    func application(application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData) {
        let tokenChars = UnsafePointer<CChar>(deviceToken.bytes)
        var tokenString = ""

        for i in 0..<deviceToken.length {
            tokenString += String(format: "%02.2hhx", arguments: [tokenChars[i]])
        }

        //Tricky line
        FIRInstanceID.instanceID().setAPNSToken(deviceToken, type: FIRInstanceIDAPNSTokenType.Unknown)
        print("Device Token:", tokenString)
    }

    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 throttle down OpenGL ES frame rates. Games should use this method to pause the game.
    }

    // [START receive_message]
    func application(application: UIApplication, didReceiveRemoteNotification userInfo: [NSObject : AnyObject],
                     fetchCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void) {
        // 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

        let alertController = UIAlertController(title: "Notification", message: "A standard alert", preferredStyle: .Alert)

        let OKAction = UIAlertAction(title: "OK", style: .Default) { (action:UIAlertAction!) in

        }
        alertController.addAction(OKAction)

        self.window?.rootViewController?.presentViewController(alertController, animated: true, completion:nil)

        // Print message ID.
//        print("Message ID: \(userInfo["gcm.message_id"]!)")

        // Print full message.
        print("%@", userInfo)
    }
    // [END receive_message]

    // [START refresh_token]
    func tokenRefreshNotification(notification: NSNotification) {
        if let refreshedToken = FIRInstanceID.instanceID().token() {
            print("InstanceID token: \(refreshedToken)")
        }

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

    // [START connect_to_fcm]
    func connectToFcm() {
        FIRMessaging.messaging().connectWithCompletion { (error) in
            if (error != nil) {
                print("Unable to connect with FCM. \(error)")
            } else {
                print("Connected to FCM.")
            }
        }
    }
    // [END connect_to_fcm]

    func applicationDidBecomeActive(application: UIApplication) {
        connectToFcm()
    }

    // [START disconnect_from_fcm]
    func applicationDidEnterBackground(application: UIApplication) {
        FIRMessaging.messaging().disconnect()
        print("Disconnected from FCM.")
    }
    // [END disconnect_from_fcm]

在我的服务器中，我使用类似的东西来推送通知：

method: 'POST',
            uri: 'https://fcm.googleapis.com/fcm/send',
            headers: {
                'Content-Type': 'application/json',
                'Authorization':'key= **THE KEY**'
            },
            body: JSON.stringify({
                "to" : " **USER INSTANCEID TOKEN** ",
                "priority":"high",
                "data" : {
                    "title": "FCM TITLE",
                    "body" : "FROM FCM",
                    "badge": "0",
                    "sound": "default"
                }
            })

我尝试到处搜索，但找不到任何解决方案，似乎无法在FCM文档中找到有关此问题的任何内容 .