Xamarin problems

Xamarin Studio
Version 5.7 (build 660)
Xamarin.iOS
Version: 8.6.0.41 (Enterprise Edition)

#1      ViewRenderer Problem
//....  Dont work correctly. When happenning dispose ViewRendere can't find control and throw NullReferenceException
  override void OnElementChanged(ElementChangedEventArgs<View> e)
    {
      base.OnElementChanged(e);
    }
//....

//.... Partial solution, it's work, but if you have subviews with gestures this code won't work correctly
  override void OnElementChanged(ElementChangedEventArgs<View> e)
    {
      base.OnElementChanged(e);
        if (e.OldElement == null)
        {
           SetNativeControl(new UIView());
        }
    }
//....

//.... Probably right solution
override void OnElementChanged(ElementChangedEventArgs<View> e)
    {
      base.OnElementChanged(e);
        if (e.OldElement == null)
        {
          var view = new UIView();
          
          view.AddSubviews(Subviews);
          
          SetNativeControl(view);
        }
    }
//....