title: how to set image on default back button of navigation bar
body: <p>I am setting back button image on navigation bar for all the view controllers using the following code in Appdelegate:</p>
  
  <pre><code>    [[UIBarButtonItem appearance] setBackButtonBackgroundImage:image forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
  </code></pre>
  
  <p>Now in one of my view controllers i pick a newimage from the gallery and save it. I want that as soon as i save this newimage, the 'image' of back button gets replaced with this 'newimage'.</p>
  
  <p>I tried following code in viewWillAppear of each and every view controller</p>
  
  <pre><code>    [self.navigationItem.backBarButtonItem setBackButtonBackgroundImage:newimage forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
  </code></pre>
  
  <p>and tried </p>
  
  <pre><code> [self.navigationItem.backBarButtonItem setImage:new];
  </code></pre>
  
  <p>this too. But all in vain.
  Image gets changed only when i run my app again and thus when code in Appdelegate gets called.</p>
  
  <p>Plz help!</p>