the application called an interface that was marshalled for a different thread. windows 8.1 store app

Question

I am developing a windows store 8.1 app using C# and xaml. When i tried to update the UI from code behind file i got an exception which is

" the application called an interface that was marshalled for a different thread"

i have added the below code to update the UI

 await  Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
                () =>
                {
                    statustextblk.Text = "Offline sync in progress...";
                }
                );

This is working fine. But i want to update the same textblack after offline sync is completed. So for this i wrote the below code, the code looks like this

await  Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
                () =>
                {
                    statustextblk.Text = "Offline sync in progress...";
                }
                );

await SharedContext.Context.OfflineStore.ScheduleFlushQueuedRequestsAsync();
                Debug.WriteLine("Refresh started");

                if (SharedContext.Context.OfflineStore != null && SharedContext.Context.OfflineStore.Open)
                    await SharedContext.Context.OfflineStore.ScheduleRefreshAsync();


                RefreshSuccess = true;
                await Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
                () =>
                {
                    statustextblk.Text = "Offline sync completed...";
                    Task.Delay(1000);
                    statustextblk.Text = "";
                }
                );

But it is not displaying the "Offline sync completed..." message in the UI.

How can i show it in the UI once the method is executed?

Can someone please help me out?

Thanks in advance

Answer 1

If you comment Task.Delay(1000), "Offline sync completed..." will show within a very short time but will disappear immediately because you set the statustextblk.Text = "".

Therefore you can refer to @Raymond said in the comment. Add modifier ‘async’ before () => and modifier ‘await’ before Task.Delay(1000); You can refer to the demo I made as following:

private async void Button_Click(object sender, RoutedEventArgs e)
    {
        await Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
            () =>
            {
                statustextblk.Text = "Offline sync in progress...";
            }
            );

        Debug.WriteLine("Refresh started");

        await Task.Delay(1000);

        //RefreshSuccess = true;
        await Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
        async () =>
        {
            statustextblk.Text = "Offline sync completed...";
            await Task.Delay(1000);
            statustextblk.Text = "";
        }
        );
    }