public async Task GetSnacksMethod()     //ottiene la lista degli snack e la applica alla ListView
        {
            var result = await SnackService.GetAllSnacksAsync();

            if (result != null)
            {
                ListView.ItemsSource = result.data.snacks;
                SelectedSnackLength  = result.data.snacks.Count;
            }
            else
            {
            }
        }