title: Swift: Draw an overlay view with some elements on screen highlighted
body: <p>I have a UIViewController which has few elements that I have drawn programmatically.</p>
  
  <p>Now I want to show few of those elements above a overlay in order to highlight them with a one-liner description. </p>
  
  <pre><code>class ExampleViewController: UIViewController {
      let element1 = UITextField()
      let element2 = UIButton()
      let overlayView = UIView()
  
      override func viewDidLoad() {
          super.viewDidLoad()
          // ADDING ELEMENTS TO VIEW
          self.view.addSubview(self.element1)
          self.element1.text = "Some text"
  
          // ...other elements...
  
          //DRAWING MY OVERLAY WITH TRANSPARENCY
          self.overlayView = UIView(frame: self.view.frame)
          self.overlayView.backgroundColor = UIColor.blackColor()
          self.overlayView.alpha = 0.4
          self.view.addSubview(self.overlayView)
  
      }
  
  }
  </code></pre>
  
  <p>Problem I am facing are the following,</p>
  
  <ol>
  <li>How do I bring the element on top of my semi-transparent overlay UIView?</li>
  <li>How do I make the elements(that I bring forth) not have semi-transparency of overlay?</li>
  </ol>
  
  <p>In other words, I want few elements to appear on top of my overlayView when I show the overlay.</p>