title: iOS 8 UITableView first row has wrong height
body: <p>I'm working on an app where I face a strange issue. I've created a UITableViewController in the storyboard and added a prototype cell. In this cell, I've added an UILabel element and this UILabel takes up the whole cell. I've set it up with Auto Layout and added left, right, top and bottom constraints. The UILabel contains some text.</p>
  
  <p>Now in my code, I initialize the the rowHeight and estimatedRowHeight of the table view:</p>
  
  <pre><code>override func viewDidLoad() {
      super.viewDidLoad()
  
      self.tableView.rowHeight = UITableViewAutomaticDimension
      self.tableView.estimatedRowHeight = 50
  }
  </code></pre>
  
  <p>And I create the cell as follows:</p>
  
  <pre><code>override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -&gt; UITableViewCell {
      var cell : UITableViewCell? = tableView.dequeueReusableCellWithIdentifier("HelpCell") as? UITableViewCell
      if(cell == nil) {
          cell = UITableViewCell(style: .Default, reuseIdentifier: "HelpCell")
      }
      return cell!
  }
  </code></pre>
  
  <p>I return two rows in my table view. Here comes my problem: the height of the first row is way to large. It appear that the second, third row etc all have a correct height. I really don't understand why this is the case. Can someone help me with this?</p>