title: nsdictionary copy vs mutable copy
body: <p>I have</p>
  
  <pre><code>NSMutableDictionary *myDictionary = [[NSMutableDictionary alloc] init];
  id dict = [myDictionary copy];
  </code></pre>
  
  <p>but is <code>dict</code> now just a regular <code>NSDictionary</code>? Or is it a copy of the <code>NSMutableDictionary</code>?</p>
  
  <p>Also, is there any way to go from mutable to non-mutable?</p>