title: Background image of back button does not appear before it is touched iOS 7
body: <p>I am experiencing some problems with <code>[UIBarButtonItem appearance]</code> for the the back button background image.</p>
  
  <p>Normally (iOS 5 and iOS 6) I was able to set the background image of the back button like this:</p>
  
  <pre><code>[[UIBarButtonItem appearance] setBackButtonBackgroundImage:backButtonImage forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
  </code></pre>
  
  <p>But at iOS 7 the background image does not appear on the back button. The weird thing is, that the background image actually appears when the back button has been touched once.</p>
  
  <p>I have tried setting the image for all states, to test if iOS 7 was using some kind of new state for an untouched back button, but that does not seem to be the case.</p>
  
  <p>Do you have any idea, what I am doing wrong?</p>