public ExampleViewModel()
        {
            CollectionItems = new ObservableCollection <Result> ();
            IsLoading       = false;
            exampleService  = new ExampleService(App.Database);

            MessagingCenter.Subscribe <ExamplePage, Result> (this, "LoadItems", (sender, e) => {
                LoadMoreItems(e);
            });

            LoadMoreCommand = new Command(() => {
                UpdateViewModel();
            });

            UpdateViewModel();
        }
		public ExampleViewModel ()
		{
			CollectionItems = new ObservableCollection<Result> ();
			IsLoading = false;
			exampleService = new ExampleService (App.Database);

			MessagingCenter.Subscribe<ExamplePage,Result> (this, "LoadItems", (sender, e) => {
				LoadMoreItems(e);
			});

			LoadMoreCommand = new Command(() => {
				UpdateViewModel ();
			});

			UpdateViewModel ();
		}