title: In iOS7, why selected cell's background color is always gray?
body: <p>set <code>cell.selectionStyle = UITableViewCellSelectionStyleBlue</code>, or even manually set <strong>Blue</strong> in storyboard, but neither of them works.</p>
  
  <p>if using <code>setSelectedBackgroundView:</code>, it may work.</p>
  
  <p>But I really want to know why method of `[cell setSelectionStyle:] not work any more in iOS 7? Is it deprecated in iOS 7? If so, why no any waring in Xcode when typing?</p>