title: What is a typedef enum in Objective-C?
body: <p>I don't think I fundamentally understand what an <code>enum</code> is, and when to use it.  </p>
  
  <p>For example:</p>
  
  <pre><code>typedef enum {
      kCircle,
      kRectangle,
      kOblateSpheroid
  } ShapeType;
  </code></pre>
  
  <p>What is really being declared here?</p>