Correct way to get the CoreDispatcher in a Windows Store app

This is the preferred way:

Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
    // Your UI update code goes here!
});

The advantage this has is that it gets the main CoreApplicationView and so is always available. More details here.

There are two alternatives which you could use.

First alternative

Windows.ApplicationModel.Core.CoreApplication.GetCurrentView().CoreWindow.Dispatcher

This gets the active view for the app, but this will give you null, if no views has been activated. More details here.

Second alternative

Window.Current.Dispatcher

This solution will not work when it's called from another thread as it returns null instead of the UI Dispatcher. More details here.

For anyone using C++/CX

Windows::ApplicationModel::Core::CoreApplication::MainView->CoreWindow->Dispatcher->RunAsync(
    CoreDispatcherPriority::Normal,
    ref new Windows::UI::Core::DispatchedHandler([this]()
{
    // do stuff
}));