title: custom backbutton not working in xcode
body: <p>i am using these code for custom back button</p>
  
  <pre><code>UIImage *buttonImage = [UIImage imageNamed:@"back-button-2.png"];
  
      //create the button and assign the image
      UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
      [button setImage:buttonImage forState:UIControlStateNormal];
  
      //set the frame of the button to the size of the image (see note below)
      button.frame = CGRectMake(0, 0, buttonImage.size.width, buttonImage.size.height);
  
      [button addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];
  
      //create a UIBarButtonItem with the button as a custom view
      UIBarButtonItem *customBarItem = [[UIBarButtonItem alloc] initWithCustomView:button];
      self.navigationItem.leftBarButtonItem = customBarItem;
  </code></pre>
  
  <p>and here is the back function</p>
  
  <pre><code>-(void)back {   
      // Tell the controller to go back
      [self.navigationController popViewControllerAnimated:YES];
  }
  </code></pre>
  
  <p>Custom back button is coming up, but it's not working. </p>