Question

例如，我需要使用CoreDispatcher在UI线程中刷新MVVM属性。

private void ButtonClick(object sender, RoutedEventArgs e)
{
    //Code not compile without keyword async
    var dispatcherResult = this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async () =>
            {
                //This method contains awaitable code
                await _scanner.ScanAsync();
            }
            );

    dispatcherResult.Completed = new AsyncActionCompletedHandler(TaskInitializationCompleted);
} 

private void TaskInitializationCompleted (IAsyncAction action, AsyncStatus status )
{
    //Do something...
}

我希望，然后 TaskInitializationCompleted 处理程序将在AFTER ScanAsync 方法完成后触发，但它在 Dispatcher.RunAsync 方法启动后立即触发之前 ScanAsync 已完成。

如何检查以真正处理完成或取消异步Dispatcher工作？

Answer 1

您可以Completed（因为await RunAsync是等待的）而不是注册DispatcherOperation事件，这将保证任何代码仅在完成调用完成后运行：

private async void ButtonClick(object sender, RoutedEventArgs e)
{
    var dispatcherResult = await this.Dispatcher
                                .RunAsync(CoreDispatcherPriority.Normal,
                                 async () =>
            {
                await _scanner.ScanAsync();
            });

    // Do something after `RunAsync` completed
}

处理异步CoreDispatcher工作完成或取消时的处理时间

1 个答案: