title: Swift enum inheritance
body: <p>Can you inherit enum in Swift? What are the rules that one should be aware of with regards to enum inheritance?</p>
  
  <p>The following test code:</p>
  
  <pre><code>enum TemperatureUnit: Int {
      case Kelvin, Celcius, Farenheit
  }
  
  enum TemperatureSubunit : Temperature {  
  }
  </code></pre>
  
  <p>generates</p>
  
  <pre><code>error: type 'TemperatureSubunit' does not conform to protocol 'RawRepresentable'
  </code></pre>