title: Is there a method to generate a standard 128bit GUID (UUID) on the Mac?
body: <p>Is there a built in function equivalent to .NET's</p>
  
  <pre><code>Guid.NewGuid();
  </code></pre>
  
  <p>in Cocoa?</p>
  
  <p>My desire is to produce a string along the lines of <code>550e8400-e29b-41d4-a716-446655440000</code> which represents a unique identifier.</p>