public static void CreateCortanaListItemsInstance()
 {
     if (_cortanaListItemsInstance == null)
     {
         _cortanaListItemsInstance = new CortanaListItemsViewModel();
     }
 }
 public static void ClearCortanaListItemsInstance()
 {
     _cortanaListItemsInstance = null;
 }
        void CortanaListItems_Loaded(object sender, RoutedEventArgs e)
        {
            CortanaListItemsViewModel viewModel = DataContext as CortanaListItemsViewModel;

            viewModel.LoadListItems(SettingsValues.SiteUrl, SettingsValues.ListTitle, SettingsValues.LoginName, SettingsValues.Password);
        }