If you have programmed Windows Phone or Windows Store apps, you may know about Dispatcher in Windows Phone or CoreDispatcher in Windows Store. In this article I will focus more on Windows Phone implementation, but basically this should be very similar in Windows Store.
In general, those dispatchers are ways to marshal UI interactions from a background context (any context that is not the UI context) to the UI. Trying to directly access (both read and write) any UI control or any view model property that has been bound to a UI control from a background context will trigger an UnauthorizedAccessException. Instead you will have to call Dispatcher.BeginInvoke(Action action) method (or Deployment.Current.Dispatcher.BeginInvoke(Action action) if you are not in a page) and put all the UI accessing codes in the action parameter.
It work perfectly fine until I tried to introduce some async logic inside.
You could do it simply this way:
Dispatcher.BeginInvoke(async () =>