NavigationItem titleview is null

Hi,

I have a Xamarin Forms project with a page renderer. In this page renderer I want to show a UIPopoverViewcontroller with some content when I tap the title in the navigationBar but when I try to access the titleview it is null.

public class MainPageRenderer : PageRenderer
    {
        public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            var pop = new UIPopoverController(this.ViewController);
            pop.BackgroundColor = UIColor.Red;
            pop.PresentFromRect(new CoreGraphics.CGRect(100, 250, 100, 100), this.NavigationItem.TitleView, UIPopoverArrowDirection.Any, true);
        }
    }