title: When does the UINavigationBar shadow show? (iOS 6)
body: <p>I am using a navigation bar with a custom background image. When I wanted to add a custom shadow image, I was surprised to find that even the default shadow image is not visible.</p>
  
  <p>iOS 6 introduced an automatic drop shadow on UINavigationBars, which I expected to see. The example project from <a href="http://www.raywenderlich.com/21703/user-interface-customization-in-ios-6" rel="nofollow">http://www.raywenderlich.com/21703/user-interface-customization-in-ios-6</a> demonstrates this.</p>
  
  <p>However, creating a new project from Xcode’s Master-Detail template does not show the shadow.</p>
  
  <p>When exactly is the shadow shown, and when is it not?</p>