public PresentationPage ActivePage {get;}

// Note: we are on the UI thread!
// A presentation view must be active
if (PresentationView.Active == null)
  return;
PresentationPage activePage = activePresentationView.ActivePage;

//check if the current page is a map page
if (activePage is MapPresentationPage)
{
  await activePresentationView.ActivateMapPageAsync();
}

//move to the QueuedTask to do something
await QueuedTask.Run(() =>
{
  // TODO
});