title: How to update UITableView at run time, after the view is loaded
body: <p>I have read several articles about UITableView, including the <a href="http://developer.apple.com/library/IOs/#documentation/UIKit/Reference/UITableView_Class/Reference/Reference.html" rel="noreferrer">official doc</a> and some on SO. But my situation seems to be different.<br>
  I want to update the Table each time the view loaded. And I must fetch the data using HTTP request.<br>
  What I got now is:  </p>
  
  <ol>
  <li>When enter the table view, I should use a non-synchronous HTTP request to update the data. Because I don't want the main thread to wait. One place to do that, is in the <code>tableView:cellForRowAtIndexPath:</code> method. So I return 0 for no data exist at the beginning.  </li>
  <li>When I get the HTTP respond, I update rows on main thread using  <code>beginUpdates endUpdates insertRowsAtIndexPaths:withRowAnimation:</code>  </li>
  <li>And I must update the "Data Source" at the same time, but how to do that?<br>
  Or should I make a daemon thread and update my data every once in a while? So that the data will be ready when TableView is loaded. </li>
  </ol>