FirebaseMessaging getToken在iOS上不起作用

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // 注册远程通知
    UNUserNotificationCenter.current().delegate = self
    let authOptions: UNAuthorizationOptions = [.alert, .badge, .sound]
    UNUserNotificationCenter.current().requestAuthorization(options: authOptions, completionHandler: {_, _ in })
    application.registerForRemoteNotifications()
    
    // 配置Firebase
    FirebaseApp.configure()
    
    // 获取令牌
    Messaging.messaging().delegate = self
    Messaging.messaging().token { token, error in
        if let error = error {
            print("Error fetching FCM registration token: \(error)")
        } else if let token = token {
            print("FCM registration token: \(token)")
        }
    }
    
    return true
}