private async void squaresListBox_SelectionChanged(object sender, Windows.UI.Xaml.Controls.SelectionChangedEventArgs e)
{
if (squaresListBox.SelectedIndex != -1)
{
categoriesListBox.ItemsSource = await Squares.GetCategories(((Squares.Square)squaresListBox.SelectedItem).id);
}
}
/// <summary>
/// Populates the page with content passed during navigation. Any saved state is also
/// provided when recreating a page from a prior session.
/// </summary>
/// <param name="sender">
/// The source of the event; typically <see cref="NavigationHelper"/>
/// </param>
/// <param name="e">Event data that provides both the navigation parameter passed to
/// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested and
/// a dictionary of state preserved by this page during an earlier
/// session. The state will be null the first time a page is visited.</param>
private async void NavigationHelper_LoadState(object sender, LoadStateEventArgs e)
{
string parameter = e.NavigationParameter as string;
squareID = parameter;
var categories = await Squares.GetCategories(parameter);
Squares.Square.Category cat = new Squares.Square.Category();
cat.id = null;
cat.name = "all";
categories.Insert(0, cat);
CategoriesListBox.ItemsSource = categories;
}