public MainPage()
{
InitializeComponent();
NavigationCacheMode = NavigationCacheMode.Required;
NavigationHelper = new NavigationHelper(this);
NavigationHelper.LoadState += navigationHelper_LoadState;
_viewModel = DataContext as MainPageViewModel;
SizeChanged += MainPageSizeChanged;
}
public ChatPage()
{
InitializeComponent();
NavigationHelper = new NavigationHelper(this);
NavigationHelper.LoadState += navigationHelper_LoadState;
NavigationHelper.SaveState += navigationHelper_SaveState;
_chatTimer = new Timer(state => _friendViewModel.Conversation.SetTypingStatus(false),
null, Timeout.Infinite, Timeout.Infinite);
}