public void BackButtonBackgroundImage()
{
using (UIBarButtonItem btn = new UIBarButtonItem()) {
#if !__TVOS__
Assert.Null(btn.GetBackButtonBackgroundImage(UIControlState.Highlighted, UIBarMetrics.Default), "Get");
btn.SetBackButtonBackgroundImage(null, UIControlState.Highlighted, UIBarMetrics.Default);
#endif
}
}