title: How to group NSDate objects by day?
body: <p>I'm setting a timeStamp property for an object.  Right now I'm just using <code>[NSDate date]</code>.  The user might create 10 objects per day.  But in the UI, I want to drop them by date. So each day will show all the objects that were created for that day.  How can I do this?  Right now it's trying to match the date and time, etc.</p>
  
  <pre><code>Example: 
  Obj1 - 2/5/12 5pm
  Obj2 - 2/5/12 12pm
  Obj3 - 2/4/12 6pm
  Obj4 - 2/1/12 1pm
  </code></pre>
  
  <p>I need to be able to group those by day, one for 2/5, 2/4, and 2/1.</p>