title: The new enum in Objective-C
body: <p>In the latest tools, a new kind of <code>enum</code>s are now allowed:</p>
  
  <pre><code>typedef enum CarType : NSUInteger {
    FourDoorCarType,
    TwoDoorCarType
  } CarType;
  </code></pre>
  
  <p>My question comes in parts:</p>
  
  <ol>
  <li><p>Why should I use this instead of the old way?</p></li>
  <li><p>Why does <code>CarType</code> appear twice? I tried skipping the first <code>CarType</code> and just leaving the first line as "<code>typedef enum : NSUInteger {</code>", and it seems to work fine. What are the drawbacks, if any?</p></li>
  <li><p>Can some types other than <code>NSUInteger</code> be used?</p></li>
  </ol>