在iOS后台获取远程推送通知消息

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // 注册远程通知
    UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound, .badge]) { (granted, error) in
        if granted {
            DispatchQueue.main.async {
                application.registerForRemoteNotifications()
            }
        }
    }
    return true
}

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
    // 获取设备的推送令牌
    let token = deviceToken.map { String(format: "%02.2hhx", $0) }.joined()
    print("Device Token: \(token)")
}

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
    // 处理接收到的推送通知
    print("Received remote notification: \(userInfo)")
    completionHandler(.newData)
}