NavigationRenderer and iOS right button

Hi,

I wrote the below renderer but no right button on iPhone simulator.
'public class NavigationPageWithHomeBtnRenderer: NavigationRenderer
{
public NavigationPageWithHomeBtnRenderer()
{ }

    public override void ViewDidLoad()
    {
        base.ViewDidLoad();
        this.NavigationItem.SetRightBarButtonItem(
            new UIBarButtonItem(UIBarButtonSystemItem.Play, (sender, args) =>
            {
                //TODO
            })
        , true);
    }
}'