在解除WP8应用程序后，UploadAsync不起作用 [英] UploadAsync doesn't work after WP8 app has been dismissed

问题描述

我有一个应用程序尝试将文件保存到SkyDrive即将关闭。

当我的应用程序在前台运行时，我的UploadAsync调用没有问题。

为了在我的应用程序关闭时将文件保存到SkyDrive，我像这样覆盖了OnBack按钮：

 protected override void OnBackKeyPress（CancelEventArgs e）
 {
 SaveSkydriveData（）; 
 base.OnBackKeyPress（e）; 
} 

SaveSkydriveData看起来像这样：

<预类= "prettyprint" 风格= "">公共异步任务SaveSkydriveData（）
{
IsolatedStorageFile商店= IsolatedStorageFile.GetUserStoreForApplication（）;
FileStream stream = store.OpenFile（" MyData.txt"，FileMode.Create）;
StreamWriter writer = new StreamWriter（stream）;
writer.Write（" blah"）;
writer.Close（）;
stream.Close（）;

FileStream readstream = store.OpenFile（" MyData.txt"，FileMode.Open）;
readstream.Position = 0;
var result = await client.UploadAsync（" me / skydrive"，" MyData.txt"，readstream，OverwriteOption.Overwrite）;
readstream.Close（）;
}

为什么这不起作用？如果在我的应用程序仍在运行时调用，SaveSkydriveData（）将按预期工作。但它似乎不适用于上述情况。

谢谢！

解决方案

UploadAsync只能在应用程序位于前台时使用。你应该考虑使用BackgroundUploadAsync（）。

谢谢，

Lin

Hi, I have an app that tries to save a file to SkyDrive when it is just about the be closed.

While my app is running in the foreground, my UploadAsync call works without a problem.

In order to save the file to SkyDrive as my app closes, I overrode the OnBack button like so:

protected override void OnBackKeyPress(CancelEventArgs e)
        {
            SaveSkydriveData();
            base.OnBackKeyPress(e);
        }

And SaveSkydriveData looks something like this:

public async Task SaveSkydriveData()
        {
            IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForApplication();
            FileStream stream = store.OpenFile("MyData.txt", FileMode.Create);
            StreamWriter writer = new StreamWriter(stream);
            writer.Write("blah");
            writer.Close();
            stream.Close();

            FileStream readstream = store.OpenFile("MyData.txt", FileMode.Open);
            readstream.Position = 0;
            var result = await client.UploadAsync("me/skydrive", "MyData.txt", readstream, OverwriteOption.Overwrite);
            readstream.Close();
        }

Why doesn't this work? SaveSkydriveData() works as expected if called while my app is still running. But it doesn't seem to work in the above scenario.

Thanks!

解决方案

UploadAsync can be only used when the app is in foreground. You should consider to use BackgroundUploadAsync() instead.

Thanks,

Lin

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