Visual Studio App Center：'await' 运算符只能在异步方法中使用

Question

我需要有关 App Center 推送通知的帮助。我想知道用户是否在他的 iOS/Android 设备上启用或禁用了推送通知。此任务应在应用程序启动时完成。我遵循了这个 App Center 教程，但是当我检查推送通知是启用还是禁用时，我收到一条错误消息。

App Center tutorial

Error CS4033: The 'await' operator can only be used within an async method. Consider marking this method with the 'async' modifier and changing its return type to 'Task'.

怎么了？我如何才能知道用户是否启用或禁用了推送通知？

using Foundation;
using UIKit;
using Microsoft.AppCenter;
using Microsoft.AppCenter.Analytics;
using Microsoft.AppCenter.Crashes;
using Microsoft.AppCenter.Push;

namespace iosprojectnew.iOS
{
    [Register("AppDelegate")]
    class Program : UIApplicationDelegate
    {
        private static Game1 game;

        internal static void RunGame()
        {
            game = new Game1();
            game.Run();
        }

        static void Main(string[] args)
        {
            UIApplication.Main(args, null, "AppDelegate");
        }

        public override void FinishedLaunching(UIApplication app)
        {      
            if (!AppCenter.Configured)
            {
                bool isEnabled = await Push.IsEnabledAsync();

                Push.PushNotificationReceived += (sender, e) =>
                {
                    // Add the notification message and title to the message
                    var summary = $"Push notification received:" +
                                        $"\n\tNotification title: {e.Title}" +
                                        $"\n\tMessage: {e.Message}";

                    // If there is custom data associated with the notification,
                    // print the entries
                    if (e.CustomData != null)
                    {
                        summary += "\n\tCustom data:\n";
                        foreach (var key in e.CustomData.Keys)
                        {
                            summary += $"\t\t{key} : {e.CustomData[key]}\n";
                        }
                    }

                    // Send the notification summary to debug output
                    System.Diagnostics.Debug.WriteLine(summary);
                };
            }


            AppCenter.Start("...", typeof(Analytics), typeof(Crashes), typeof(Push));
            RunGame();
        }
    }
}

Answer 1

使用 await 的方法必须标记为 async。尝试在 void FinishedLaunching 之前添加 async 关键字：

public override async void FinishedLaunching(UIApplication app) { ... }

Answer 2

await 关键字只能用于异步方法，但此方法是重写方法，因此您不能转换为任务。

无论如何，你可以像这样在使用异步的地方编写行代码：

bool isEnabled = await Push.IsEnabledAsync().Result;

Visual Studio App Center：'await' 运算符只能在异步方法中使用

Visual Studio App Center: The 'await' operator can only be used within an async method

c#

xamarin.ios

xamarin.android

monogame

visual-studio-app-center