title: How to get rid of UIAppearance when not needed?
body: <p>In my AppDelegate I use UIAppearance to set my own NavigationBar with this code :</p>
  
  <pre><code>[[UINavigationBar appearance] setTintColor:[UIColor blackColor]];
  [[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"nav5.png"] forBarMetrics:UIBarMetricsDefault];
  </code></pre>
  
  <p>But some views of my application don't need it. How can I get rid of it so I may only use IB in concerned views ?</p>