title: Add custom button to navigation controller without border
body: <p>I add custom button to navigation controller</p>
  
  <pre>
      UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"back.png"]
                                                                     style:UIBarButtonItemStylePlain
                                                                    target:self
                                                                    action:@selector(backAction)];
      self.navigationItem.leftBarButtonItem = backButton;
  </pre>
  
  <p>it works fine, but button appears bordered. How can I fix that?</p>
  
  <p><strong>UPDATE</strong>
  I found solution</p>
  
  <pre>   
   UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 25, 25)];
      [button setImage:[UIImage imageNamed:@"back.png"] forState:UIControlStateNormal];
      [button addTarget:self action:@selector(buttonFavoriteClicked) forControlEvents:UIControlEventTouchUpInside];
      UIBarButtonItem *back = [[UIBarButtonItem alloc] initWithCustomView:button];
      [button release];
   </pre>   
  
  <pre><code>self.navigationItem.leftBarButtonItem = back;
  </code></pre>