在UWP中杀死应用程序后，如何运行进程内后台任务？

Question

我希望我的进程中后台任务在应用被杀死时运行。 这是为了不断跟踪用户的位置变化。 没有地理围栏。 那么，在UWP中有没有办法做到这一点？ 以下是我的代码，该应用程序被杀死时被杀死。 在Android（Sticky后台服务）和iOS上仅花费了几分钟。 不能将WindowsRuntimeComponent与进程外任务一起使用，因为我有很多代码可以从Xamarin Forms PCL中引用。 我正在寻找的等同物是Android Sticky Background Service。

private async void RegisterBackgroundTask() 
{
    var backgroundAccessStatus = await BackgroundExecutionManager.RequestAccessAsync();

    if (backgroundAccessStatus == BackgroundAccessStatus.AllowedSubjectToSystemPolicy)
    {
        UnregisterTask(TaskName);
        RegisterTask(TaskName);
    }
}

private async void RegisterTask(string taskName)
{
    BackgroundTaskBuilder taskBuilder = new BackgroundTaskBuilder
    {
        Name = taskName,
    };

    var trigger = new ApplicationTrigger();
    taskBuilder.SetTrigger(trigger);

    var registration = taskBuilder.Register();
    await trigger.RequestAsync();
}


protected override void OnBackgroundActivated(BackgroundActivatedEventArgs args)
{
    Debug.WriteLine("Background " + args.TaskInstance.Task.Name + " Starting...");
    SendToast("Hi this is background Task");
    //
    // Query BackgroundWorkCost
    // Guidance: If BackgroundWorkCost is high, then perform only the minimum amount
    // of work in the background task and return immediately.
    //
    var cost = BackgroundWorkCost.CurrentBackgroundWorkCost;
    var settings = ApplicationData.Current.LocalSettings;
    settings.Values["BackgroundWorkCost"] = cost.ToString();

    //
    // Associate a cancellation handler with the background task.
    //
    args.TaskInstance.Canceled += new BackgroundTaskCanceledEventHandler(OnCanceled);

    //
    // Get the deferral object from the task instance, and take a reference to the taskInstance;
    //
    _deferral = args.TaskInstance.GetDeferral();
    _taskInstance = args.TaskInstance;

    _periodicTimer = ThreadPoolTimer.CreatePeriodicTimer(new TimerElapsedHandler(PeriodicTimerCallback), TimeSpan.FromSeconds(1));
}

private void OnCanceled(IBackgroundTaskInstance sender, BackgroundTaskCancellationReason reason)
{
    //
    // Indicate that the background task is canceled.
    //
    _cancelRequested = true;
    _cancelReason = reason;

    SendToast("Background " + sender.Task.Name + " Cancel Requested...");
}

private void PeriodicTimerCallback(ThreadPoolTimer timer)
{
    if ((_cancelRequested == false) && (_progress < 100))
    {
        _progress += 10;
        _taskInstance.Progress = _progress;
        SendToast("Timer Went Off!!");
    }
    else
    {
        _periodicTimer.Cancel();

        var key = _taskInstance.Task.Name;

        //
        // Record that this background task ran.
        //
        String taskStatus = (_progress < 100) ? "Canceled with reason: " + _cancelReason.ToString() : "Completed";
        var settings = ApplicationData.Current.LocalSettings;
        settings.Values[key] = taskStatus;
        Debug.WriteLine("Background " + _taskInstance.Task.Name + settings.Values[key]);
        SendToast(taskStatus);
        //
        // Indicate that the background task has completed.
        //
        _deferral.Complete();
    }

}

public static void SendToast(string message)
{
    var template = ToastTemplateType.ToastText01;
    var xml = ToastNotificationManager.GetTemplateContent(template);
    var elements = xml.GetElementsByTagName("text");
    var text = xml.CreateTextNode(message);

    elements[0].AppendChild(text);
    var toast = new ToastNotification(xml);
    ToastNotificationManager.CreateToastNotifier().Show(toast);
}