IAsyncOperation 是一个地铁异步操作。您可以等待的 IAsyncOperation 。

IAsyncOperation is a metro asynchronous operation. You can await an IAsyncOperation.

不过，您不能使用 IAsyncOperation 与 Task.WhenAll 或任务。 WhenAny 。要使用 IAsyncOperation 情况下使用这些方法，你应该叫 StartAsTask 扩展方法，因为这样的：

However, you can't use IAsyncOperation with Task.WhenAll or Task.WhenAny. To use IAsyncOperation instances with these methods, you should call the StartAsTask extension method, as such:

var folder = Windows.Storage.ApplicationData.Current.LocalFolder;
var fileTask = folder.GetFileAsync("text.txt").StartAsTask();