title: Adding a custom UIBarButtonItem to a UINavigationBar
body: <p>I am trying to have a large plus button as a right bar button, the code below worked while it was in a storyboard, but after moving everything to xib files and separate .swift files, this was the only thing that broke.</p>
  
  <pre><code>let button = UIButton(type: .Custom)
  button.setTitle("+", forState: .Normal)
  button.titleLabel?.font = UIFont.systemFontOfSize(20.0)
  button.frame = CGRectMake(0, 0, 100, 40)
  self.navigationItem.rightBarButtonItem = UIBarButtonItem(customView: button)
  self.navigationItem.rightBarButtonItem = UIBarButtonItem(title: "+", style: .Plain, target: self, action: #selector(GroupNavViewController.onCreate))
  self.navigationItem.rightBarButtonItem?.setTitleTextAttributes([NSFontAttributeName:UIFont.systemFontOfSize(40)], forState: .Normal)
  </code></pre>
  
  <p>The UINavigationController is its own .swift file with no xib file.</p>
  
  <p>I can't figure out why it worked in the storyboard, but now it doesn't.</p>
  
  <p>Ideally, I'd like to have a large plus button (as the normal font size seems a bit too small)</p>