title: In iOS 7 if I hide the status bar with the `prefersStatusBarHidden` method, the navigation bar shrinks/loses height. Can I stop this behaviour?
body: <p>On iOS 7, if I use the <code>prefersStatusBarHidden</code> method and return an instance variable that can be changed:</p>
  
  <pre><code>- (BOOL)prefersStatusBarHidden {
      return self.statusBarShouldBeHidden;
  }
  </code></pre>
  
  <p>And I change the instance variable, thus hiding the status bar, the navigation bar loses the 20pt of height that the status bar occupies. I don't want this, however. Is it possible to hide the status bar <em>but keep the height of the navigation bar</em>?</p>