title: children UIViews to inherit parent transparency level
body: <p>For whatever reason, sometimes when I set the transparency level of a UIView, the transparency level cascades to all of its children subviews. But sometimes it does not. I am not sure why. I don't think I ever do anything special. So what are the conditions for making sure that a child view inherits the transparency level of its parent? By transparency level, I mean <code>alpha</code></p>
  
  <p><strong>Particular Case</strong></p>
  
  <p>I have successfully placed a UISearchBar as the subview of a <code>self.navigationItem.titleView</code>. But the UISearchBar's TextField and Images (magnifying glass and delete X mark) are not taking on the transparency of the parent view.</p>