title: Navigation bar with UIImage for title
body: <p>I want to customize my app's look by using a logo image as the navigation bar's title, instead of plain text. When I use this code</p>
  
  <pre><code>let logo = UIImage(named: "logo.png")
  self.navigationItem.titleView = logo;
  </code></pre>
  
  <p>I get the error "UIImage is not convertible to UIView". How can I do this correctly?</p>