title: how reference copy is handled in Objective-C?
body: <h2>Object graph</h2>
  
  <pre>
        [Instance A]
           tree
         /       \
        /         \
       /           \
      &darr;             &darr;
  [Instance B]     [Instance C]
   apple              bug
  </pre>
  
  <h2>Question</h2>
  
  <p><em>Instance A</em> has to reference copies to <em>Instance B</em> and <em>Instance C</em>.</p>
  
  <p>If I retain or release <em>Instance A</em>, which has references to the other two instances, what happens to the various reference counts?</p>