I have a button inside a listview, but clicking the button returns the error:
Exception thrown: 'System.InvalidCastException'. **
**In line: ((ContentPage)((ListView)((StackLayout)((StackLayout)b.Parent).Parent).Parent).Parent).DisplayAlert("Clicked", item.Title.ToString() + " button was clicked", "OK");

What is wrong?

public class ListViewButton : ContentPage
{
    public class ListItem
    {
        public string Source { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }
        public string Price { get; set; }
    }
    public ListViewButton()
    {
        var listView = new ListView();
        listView.ItemsSource = new ListItem[] {
            new ListItem {Title = "First", Description="1st item", Price="$100.00"},
            new ListItem {Title = "Second", Description="2nd item", Price="$200.00"},
            new ListItem {Title = "Third", Description="3rd item", Price="$300.00"}
        };
        listView.RowHeight = 100;   
        listView.BackgroundColor = Color.Black;
        listView.HasUnevenRows = true;
        listView.ItemTemplate = new DataTemplate(typeof(ListItemCell));
        Content = listView;

        listView.ItemTapped += async (sender, e) =>
        {
            ListItem item = (ListItem)e.Item;
            await DisplayAlert("Tapped", item.Title.ToString() + " was selected.", "OK");
            ((ListView)sender).SelectedItem = null;
        };

        this.Padding = new Thickness(0, Device.OnPlatform(20, 0, 0), 0, 0);
    }


    class ListItemCell : ViewCell
    {
        public ListItemCell()
        {

            Label titleLabel = new Label
            {
                HorizontalOptions = LayoutOptions.Start,
                FontSize = 20,
                FontAttributes = Xamarin.Forms.FontAttributes.Bold,
                TextColor = Color.White
            };
            titleLabel.SetBinding(Label.TextProperty, "Title");

            Label descLabel = new Label
            {
                HorizontalOptions = LayoutOptions.Start,
                FontSize = 12,
                TextColor = Color.White
            };
            descLabel.SetBinding(Label.TextProperty, "Description");


            StackLayout viewLayoutItem = new StackLayout()
            {
                HorizontalOptions = LayoutOptions.Start,
                Orientation = StackOrientation.Vertical,
                WidthRequest = 120,
                Children = { titleLabel, descLabel }
            };

            Label priceLabel = new Label
            {
                HorizontalOptions = LayoutOptions.Center,
                FontSize = 25,
                TextColor = Color.Aqua
            };
            priceLabel.SetBinding(Label.TextProperty, "Price");

            var button = new Button //ListButton // Android workaround
            {
                Text = "Buy Now",
                BackgroundColor = Color.Teal,
                HorizontalOptions = LayoutOptions.EndAndExpand
            };
            string titulo;
            button.SetBinding(Button.CommandParameterProperty, new Binding("."));
            button.Clicked += (sender, e) =>
            {
                var b = (Button)sender;
                var item = (ListItem)b.CommandParameter;
                ((ContentPage)((ListView)((StackLayout)((StackLayout)b.Parent).Parent).Parent).Parent).DisplayAlert("Clicked", item.Title.ToString() + " button was clicked", "OK");

            };

            StackLayout viewButton = new StackLayout()
            {
                HorizontalOptions = LayoutOptions.EndAndExpand,
                Orientation = StackOrientation.Horizontal,
                WidthRequest = 260,
                Children = { priceLabel, button }
            };


            StackLayout viewLayout = new StackLayout()
            {
                HorizontalOptions = LayoutOptions.StartAndExpand,
                Orientation = StackOrientation.Horizontal,
                Padding = new Thickness(5, 10, 5, 15),
                Children = { viewLayoutItem, viewButton }
            };

            View = viewLayout;
        }

    }

}