title: UITableView row animation duration and completion callback
body: <p>Is there a way to either specify the duration for UITableView row animations, or to get a callback when the animation completes?</p>
  
  <p>What I would like to do is flash the scroll indicators after the animation completes. Doing the flash before then doesn't do anything. So far the workaround I have is to delay half a second (that seems to be the default animation duration), i.e.:</p>
  
  <pre><code>[self.tableView insertRowsAtIndexPaths:newRows
                        withRowAnimation:UITableViewRowAnimationFade];
  [self.tableView performSelector:@selector(flashScrollIndicators)
                       withObject:nil
                       afterDelay:0.5];
  </code></pre>