c# - Windows 8 - 在 For 循环中异步等待时出现线程错误

Question

我正在尝试在我的 Windows 8 应用程序中加载保存的数据。所有方法都是异步的。当 await GetStoredActivitiesInFolder(groupFolder); 第二次在 for 循环中运行时，我得到一个错误，因为线程仍在处理第一个(我猜)。

错误(当我删除上面这行代码时错误消失了):

An exception of type 'System.Runtime.InteropServices.COMException' occurred in mscorlib.dll but was not handled in user code

Additional information: The application called an interface that was marshalled for a different thread. (Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THREAD))

我的代码:

 public async void LoadActivities()
    {
        StorageFolder storageFolder = ApplicationData.Current.LocalFolder;

        StorageFolder activityFolder = await storageFolder.CreateFolderAsync(App.AppSettings.ActivityDirectory, CreationCollisionOption.OpenIfExists);

        IReadOnlyList<StorageFolder> groupFolders = await activityFolder.GetFoldersAsync();

        ObservableCollection<ActivityDataGroup> groups = new ObservableCollection<ActivityDataGroup>();

        foreach (var groupFolder in groupFolders)
        {
            ActivityDataGroup group = new ActivityDataGroup();
            group.GroupName = groupFolder.Name;

            ICollection<ActivityViewModel>  activities = await GetStoredActivitiesInFolder(groupFolder);

            foreach (var activity in activities)
            {
                group.Items.Add(activity);
            }

            AllGroups.Add(group);

        }

        this.IsDataLoaded = true;
    }

Answer 1

我认为您的 GetStoredActivitiesInFolder 有可能在非 UI 线程上返回，那么您可以修改它使其不返回，或者执行类似的操作以确保您在 UI 线程上更新 View 绑定(bind)项目，例如像那样:

await Dispatcher.RunAsync(
    CoreDispatcherPriority.High,
    () =>
    {
        AllGroups.Add(group);
    };