由网友(Indulge（迁就）)分享简介：我写一个地铁的应用程序。I am writing a metro app.本作品：HttpClient client = new HttpClient();var bytes = await client.GetByteArrayAsync(new Uri("www.microsoft.com"));这不：var...

我写一个地铁的应用程序。

I am writing a metro app.

本作品：

    HttpClient client = new HttpClient();
    var bytes = await client.GetByteArrayAsync(new Uri("www.microsoft.com"));

这不：

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

第一个返回一个任务＆LT;>，第二个返回IAsyncOperation＆LT;>

The first one returns a Task<>, the second one return an IAsyncOperation<>

有什么区别？为什么会有两种不同类型？如何解决第二个样品？

What is the difference? Why are there two different types? How can I fix the second sample?

推荐答案

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();