title: Does NSSet's containsObject: test for pointer equality or value equality?
body: <p>Say I have an <code>NSSet</code> with a string in it. If I send <code>containsObject:</code> with another string which is a different pointer but the exact same string value, will that return <code>YES</code>?</p>
  
  <p>Also, is it the same story when it comes to <code>removeObject:</code>? I.e., different objects with different pointers but the same string values will cause removal?</p>