c# – 启动时运行后台任务

我可以看到任务在调试时完全注册,但仍然不知道为什么它在启动时不起作用.

async void RequestBackgroundAccess()
{
    BackgroundAccessStatus backgroundStatus = await BackgroundExecutionManager.RequestAccessAsync();

    if (backgroundStatus != BackgroundAccessStatus.Denied && backgroundStatus != BackgroundAccessStatus.Unspecified)
    {
        RegisterBackgroundThread();
    }
    else
    {
        Debug.WriteLine("[Background Access] Denied.");
    }
}

void RegisterBackgroundThread()
{
    var taskRegistered = false;
    var exampleTaskName = "Bot";

    foreach (var bgTask in BackgroundTaskRegistration.AllTasks)
    {
        if (bgTask.Value.Name == exampleTaskName)
        {
            taskRegistered = true;
            Debug.WriteLine("[Background Task] Registered.");
            break;
        }
    }

    if (taskRegistered == false)
    {
        Debug.WriteLine("[Background Task] Registering...");

        var builder = new BackgroundTaskBuilder();

        builder.Name = exampleTaskName;
        builder.TaskEntryPoint = "Tasks.Bot";
        builder.SetTrigger(new SystemTrigger(SystemTriggerType.UserPresent,false));

        BackgroundTaskRegistration task = builder.Register();
        Debug.WriteLine("[Background Task] Registered.");
    }
}

Bot.cs

namespace Tasks
{
    public sealed class Bot : IBackgroundTask
    {
        BackgroundTaskDeferral serviceDeferral;

        public void Run(IBackgroundTaskInstance taskInstance)
        {
            this.serviceDeferral = taskInstance.GetDeferral();
            ToastNotification("Starting...");
        }

        void ToastNotification(String message)
        {
            XmlDocument toastXml = ToastNotificationManager.GetTemplateContent(ToastTemplateType.ToastText01);

            XmlNodeList stringElements = toastXml.GetElementsByTagName("text");
            stringElements[0].AppendChild(toastXml.CreateTextNode(message));

            ToastNotification toast = new ToastNotification(toastXml);
            ToastNotificationManager.CreateToastNotifier().Show(toast);
        }
    }
}