title: CoreData convert NSNumbers to BOOL
body: <p>I have an entity in my CoreData model which has a boolean field.  This is stored on the CoreData Entity as an <code>NSNumber</code>.  What I'd like is for the accessors to use <code>BOOL</code> and not <code>NSNumber</code>, so I can use</p>
  
  <pre><code>comment.isActive = YES;
  </code></pre>
  
  <p>instead of:</p>
  
  <pre><code>BOOL isCommentActive = [NSNumber numberWithBool:comment.isActive];
  </code></pre>
  
  <p>I was going to change the code in the auto-generated entity class file, but I was told not to do this since it overwrites each time I extract the model.  </p>
  
  <p>I have a category for the entity, and I tried coding an accessor which converts it to a <code>BOOL</code> of the same name, but this just resulted in me getting stuck into a loop.</p>
  
  <p>Some people have mentioned method twizzling, but it sounds pretty hacky to me.  Should i just create an accessor which returns a primitive of a different name?  </p>