title: Create objective-c class instance by name?
body: <p>Is it possible to create an instance of a class by name? Something like:</p>
  
  <pre><code>NSString* className = @"Car";
  id* p = [Magic createClassByName:className];
  [p turnOnEngine];
  </code></pre>
  
  <p>I don't know if this is possible in objective-c but seems like it would be,</p>