title: How do we return an optional enum value from Swift to Obj-C?
body: <p>We know how to expose Swift enums to Obj-C:</p>
  
  <pre><code>@objc enum Animal: Int {
      case Cat, Dog
  }
  </code></pre>
  
  <p>But the compiler complains that the following "cannot be represented in Obj-C":</p>
  
  <pre><code>func myAnimal() -&gt; Animal? {
      if hasPet() {
           return .Cat
      } else {
           return nil
      }
  }
  </code></pre>
  
  <p>Ideas?</p>