title: IBDesignable never finishes updating UITableViewCell in storyboard
body: <p>This is a similar question to <a href="https://stackoverflow.com/questions/25573434/ibdesignable-and-uitableviewcell">this</a> but not quite the same.</p>
  
  <p>I have created a subclass of UITableViewCell which references a custom nib and marked it as @IBDesignable. Changes that are made both in code and from the .xib file display correctly in the simulator and on a device but not in the storyboard.</p>
  
  <pre><code>import UIKit
  
  @IBDesignable class TextFieldTableViewCell: UITableViewCell {
  
      var view: UIView!
  
      required init?(coder aDecoder: NSCoder) {
          super.init(coder: aDecoder)
  
          setup()
      }
  
      override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
          super.init(style: style, reuseIdentifier: reuseIdentifier)
  
          setup()
      }
  
      func setup() {
          view = loadViewFromNib()
          view.frame = bounds
          view.autoresizingMask = [UIViewAutoresizing.FlexibleWidth, UIViewAutoresizing.FlexibleHeight]
          contentView.addSubview(view)
      }
  
      func loadViewFromNib() -&gt; UIView {
  
          let bundle = NSBundle(forClass: self.dynamicType)
          let nib = UINib(nibName: "TextFieldTableView", bundle: bundle)
          let view = nib.instantiateWithOwner(self, options: nil)[0] as! UIView
  
          return view
      }
  }
  </code></pre>
  
  <p>The storyboard displays a permanent "Designables Updating".</p>
  
  <p><a href="https://i.stack.imgur.com/uA3jHm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uA3jHm.png" alt="Designables Updating"></a></p>
  
  <p>Breaking the problem down into a less complex test of only subclassing a UITableViewCell and marking it as @IBDesignable results in the same permanent "Designables Updating".</p>
  
  <pre><code>import UIKit
  
  @IBDesignable class TextFieldTableViewCell: UITableViewCell {
  
      required init?(coder aDecoder: NSCoder) {
          super.init(coder: aDecoder)
      }
  
      override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
          super.init(style: style, reuseIdentifier: reuseIdentifier)
      }
  
  }
  </code></pre>
  
  <p>Has anyone had success with creating a @IBDesignable UITableViewCell subclass? This is happening in Xcode 7 beta 6 and beta 5.</p>