title: viewWithTag returns nil for UITableViewCell
body: <p>I have a <code>UITableView</code> with a prototype <code>UITableViewCell</code> with the identifier <code>contact</code>. In interface builder, I built the cell correctly and have all the elements set to the right tags. When I try to edit a <code>UILabel</code> in the cell that has the tag 101 using <code>cell.viewWithTag</code>, the method returns nil. This seems to only be a problem on iOS 8. I am using storyboards and Swift. Here is the code in <code>tableView:cellForRowAtIndexPath:</code></p>
  
  <pre><code>let contact = contacts[indexPath.row]
  println("Contact: \(contact)")
  cell = tableView.dequeueReusableCellWithIdentifier("contact") as UITableViewCell
  (cell.contentView.viewWithTag(101) as UILabel).text = contact["name"]! as String
  </code></pre>