title: NSNumber as key for NSDictionary
body: <p>I was wondering how keys work in a NSDictionary.  Usually, I will use a NSString as a key for example:</p>
  
  <pre><code>NSString *stringKey = @"stringKey";
  [mydict objectForKey:stringKey];
  </code></pre>
  
  <p>What if I wanted to use a NSNumber:</p>
  
  <pre><code>NSNumber *numberKey = [NSNumber numberWithInt:3];
  [mydict objectForKey:numberKey];
  </code></pre>
  
  <p>Does the dictionary go look for the key with number 3?  or would it just compare the address of the numberKey?</p>