public GroceryItemDetailPageViewModel(GroceryItem item = null)
 {
     if (item != null)
     {
         Item = item;
         Title = item.Name;
     }
     else
     {
         Item = new GroceryItem { Name = "New Grocery Item" };
         Title = "New Grocery Item";
     }
 }
 public GroceryItemDetailPage(GroceryItem item = null)
 {
     InitializeComponent();
     BindingContext = new GroceryItemDetailPageViewModel(item);
 }