title: Revise background color between UISearchBar and keyboard when the search filed get focus
body: <p>When the search field get focus, there is a black transparent view between search bar and keyboard, just like in iPhone email app, when you want to search an email, you click the search field first, there is a black transparent view appear. When you enter some words, there will be a result table view instead. And if you tap the view, the key board will close and the search filed will lose focus.</p>
  
  <p>Now, I want to change the color of this view, for example to red transparent view. I have try it by using inputAccessoryView. But there still has a black one under it and I have to add tap action for it.</p>
  
  <p>Is there any property can edit it?</p>