title: set background image navigation bar
body: <p>So I am try to set a background image for a navigation bar in MonoTouch. The image will be the same everywhere. How would i do this?</p>
  
  <p>In the viewdid load: <code>NavBar.SetBackgroundImage(UIImage.FromFile ("btn-title-bar.png"));</code></p>
  
  <p>doesn't work.</p>