c＃usp文件夹选择器子文件夹

Question

使用Windows 10 UWP应用程序中的文件夹选择器允许用户选择文件夹：

var folderPicker = new Windows.Storage.Pickers.FolderPicker();  
folderPicker.SuggestedStartLocation =  Windows.Storage.Pickers.PickerLocationId.Desktop;
folderPicker.FileTypeFilter.Add("*");

Windows.Storage.StorageFolder folder = await folderPicker.PickSingleFolderAsync();

我可以通过以下方式获取子文件夹列表：

  Task<IReadOnlyList<StorageFolder>> subFolders = SubFolders(folder);
  private async Task<IReadOnlyList<StorageFolder>> SubFolders(StorageFolder folder)
  {
      IReadOnlyList<StorageFolder> folderList = await folder.GetFoldersAsync();
      return folderList;
  }

当我遍历列表时：

  foreach (StorageFolder sf in subFolders)  
  {
       StorageFile f = await sf.GetFileAsync("something.dat");
  }

它在GetFileAsync上崩溃，这是安全设计还是我在做些傻事？

我输出视图的所有内容是：

线程0x2690已退出，代码为0（0x0）。

有人帮忙吗？