应用程序启动后，如何为用户订阅主题以获取通知？答案

【问题标题】：How can I subscribe user to a topic for notifications as soon as app starts up?应用程序启动后，如何为用户订阅主题以获取通知？
【发布时间】：2017-05-23 23:56:22
【问题描述】：

我正在使用 HTTP POST 向应用程序上的所有用户发送通知。为此，我需要订阅一个名为“global”的主题。我希望每个用户都自动订阅此主题，以确保他们收到通知（假设他们已打开通知）。

我应该将订阅放在我的代码中的哪个位置，以确保它们始终被订阅？我担心我把它放错了地方，他们永远不会被订阅。我试图在 didFinishLaunchingWithOptions 结束时订阅，但现在在这里订阅似乎还为时过早（我猜是因为用户可能还没有接受通知提示？）。

目前订阅在 didRegisterForRemoteNotificationsWithDeviceToken 中，但是在第一个应用程序运行时不会调用它，所以为了让它工作，我必须第二次运行应用程序......这是我在 AppDelegate 中的相关代码：

import UIKit
import Firebase
import FirebaseMessaging
import UserNotifications

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate, FIRMessagingDelegate {

var window: UIWindow?


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

    FIRApp.configure()

    if #available(iOS 10.0, *) {
        let authOptions: UNAuthorizationOptions = [.alert, .badge, .sound]
        UNUserNotificationCenter.current().requestAuthorization(
            options: authOptions,
            completionHandler: {_, _ in })

        // For iOS 10 display notification (sent via APNS)
        UNUserNotificationCenter.current().delegate = self
        // For iOS 10 data message (sent via FCM)
        FIRMessaging.messaging().remoteMessageDelegate = self

    } else {
        let settings: UIUserNotificationSettings =
            UIUserNotificationSettings(types: [.alert, .badge, .sound], categories: nil)
        application.registerUserNotificationSettings(settings)
    }

    application.registerForRemoteNotifications()

    return true
}



func applicationReceivedRemoteMessage(_ remoteMessage: FIRMessagingRemoteMessage) {
    print("applicationReceivedRemoteMessage")
}



func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
    if let refreshedToken = FIRInstanceID.instanceID().token() {
        print("InstanceID token: \(refreshedToken)")
        FIRMessaging.messaging().subscribe(toTopic: "/topics/global")
    }
}



@available(iOS 10.0, *)
func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
    completionHandler(UNNotificationPresentationOptions.alert)
}



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



func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any], fetchCompletionHandler completionHandler: @escaping (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.
}

【问题讨论】：

标签： ios firebase swift3 apple-push-notifications firebase-cloud-messaging

【解决方案1】：

您需要在两个地方订阅主题。

FIRApp.configure() 之后的一个。同时更新 Firebase iOS SDK 版本。好像您使用的是旧版本。

根据新版本 (FirebaseMessaging 2.0.1)。

if Messaging.messaging().fcmToken != nil {
    Messaging.messaging().subscribe(toTopic: “foo”)
}

然后是刷新令牌时的第二个。

func messaging(_ messaging: Messaging, didRefreshRegistrationToken fcmToken: String) {
    Messaging.messaging().subscribe(toTopic: “foo”)
}

这是原始答案的链接。检查贡献者提供的答案。

https://github.com/firebase/quickstart-ios/issues/307

【讨论】：

【解决方案2】：

在 Firebase Messaging 4.0.4 中将其添加到 didRegisterForRemoteNotificationsWithDeviceToken 方法中，剩下的工作就完成了

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

【讨论】：

【解决方案3】：

在这个didReceiveRegistrationToken方法中应该增加订阅方法，这样每当token刷新时，就会自动订阅主题。

func messaging(_ messaging: Messaging, didReceiveRegistrationToken fcmToken: String) {

Messaging.messaging().subscribe(toTopic: "TestTopic"){ error in
            if error == nil{
                print("Subscribed to topic")
            }
            else{
                print("Not Subscribed to topic")
            }
        }
}

【讨论】：