title: Swift enum raw value: not working with CGFloat = -1.0
body: <p>What does this not work?</p>
  
  <pre><code>enum Aspect : CGFloat {
      case Clockwise = 1.0
      case Anticlockwise = -1.0
  }
  </code></pre>
  
  <p>On Anticlockwise line I'm told that  'raw value for enum case must be a literal'</p>