title: UIBarButtonItem Title Change
body: <p>I have the following UIBarButton Item:</p>
  
  <pre><code>  UIButton *backButton = [[UIButton alloc] initWithFrame:CGRectMake(0.0f, 100.0f, 45.0f, 30.0f)];
      [backButton setBackgroundImage:backButtonImage forState:UIControlStateNormal];
      [backButton addTarget:self action:@selector(back:) forControlEvents:UIControlEventTouchDown];
      backButton.titleLabel.text = @"Back";
      backButton.titleLabel.font = [UIFont fontWithName:@"texgyreadventor-regular.otf" size:20.0f];
      backButton.titleLabel.textColor = [UIColor whiteColor];
      UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
      _backItem = backItem;
  </code></pre>
  
  <p>In some other method, I set it to be on the navigation bar as follows:</p>
  
  <p><code>[self.navigationItem setLeftBarButtonItem:_backItem];</code></p>
  
  <p>So far, everything works as expected. But right before I add it on the navigation bar on top, I would like to change its text. Here's one the things I tried doing: </p>
  
  <p><code>self.navigationItem.leftBarButtonItem.title = @"NEW TITLE";</code></p>
  
  <p>This however, does not work. How can I add a title during runtime on the fly?</p>