c# - MusicProperties 为什么为空？

Question

我的代码部分在这里。我有一个列表类。

StorageFolder libraryFolder = KnownFolders.MusicLibrary ;
        IReadOnlyList<IStorageItem> fileList = await libraryFolder.GetItemsAsync();
        foreach (StorageFile file in fileList)
        {
            MusicProperties properties = await file.Properties.GetMusicPropertiesAsync();
           .......

我在这里得到空值。

 MusicProperties properties = await file.Properties.GetMusicPropertiesAsync();

有人知道吗？