title: Dynamic Height UITableViewCell data wrong order
body: <p>Is it appropriate to call <code>[tableView beginUpdates]</code> and [<code>tableView endUpdates]</code> in <code>cellforRowAtIndexPath</code>?  </p>
  
  <p>I am trying to dynamically expand cell heights based on the content within the cell.  When I use [<code>tableView beginUpates]</code> and [<code>tableView endUpdates]</code> in <code>cellForRowAtIndexPath</code>, the output looks ok.  However, once I start scrolling, data in the cells becomes ordered incorrectly and sometimes the bar separator between table cells disappears.  </p>
  
  <p>Should I not be using <code>[tableView beginUpdates]</code> and <code>[tableView endUpdates]</code> for this?</p>
  
  <p>Thanks!</p>