/// <summary>
/// Creates a NavigationService instance.
/// </summary>
/// <param name="frame">The page frame.</param>
internal NavigationService(Frame frame)
{
try
{
FrameFacade = new FrameFacade(frame);
FrameFacade.Navigated += (s, e) =>
{
if (e.PageType == UniversalApp.Current.DefaultPage)
{
ClearHistory();
}
// KEEP THIS EVENT REGISTERED: without having this empty event registered, for whatever reason no navigation takes place
// Navigation method calls are moved to UniversalPage, to ensure the call order of ViewModel navigation events is aligned
// with the one of a Page.
};
}
catch (Exception)
{
// exception in ShareTarget here.
}
}
/// <summary>
/// Save the navigation state.
/// </summary>
public void SaveNavigation()
{
// it is possible to close the application before we have navigated and created state
if (CurrentPageType == null)
{
return;
}
var state = FrameFacade.GetPageStateContainer(GetType());
if (state == null)
{
throw new InvalidOperationException("State container is unexpectedly null");
}
state[CURRENT_PAGE_TYPE_KEY] = CurrentPageType.ToString();
try { state[CURRENT_PAGE_PARAM_KEY] = CurrentPageParam; }
catch
{
throw new Exception("Failed to serialize page parameter, override/implement ToString()");
}
state[NAVIGATE_STATE_KEY] = FrameFacade?.GetNavigationState();
}
