private async void AddItem_Clicked(object sender, EventArgs e)
{
Category Category = new Category();
CategoryDetailPage CategoryPage = new CategoryDetailPage();
CategoryPage.BindingContext = Category;
await Navigation.PushAsync(CategoryPage);
}
private async void OnItemSelected(object sender, SelectedItemChangedEventArgs e)
{
Category selectedCategory = (Category)e.SelectedItem;
CategoryDetailPage CategoryPage = new CategoryDetailPage(selectedCategory.Id);
CategoryPage.BindingContext = selectedCategory;
await Navigation.PushAsync(CategoryPage);
}