title: Custom UIView class allways crash when initialized
body: <p>I've created a simple custom UIView class.</p>
  
  <pre><code>    import Foundation
  import UIKit
  
  class customShop : UIView{
  
      var bannerViewHight: NSLayoutConstraint!
      var bannerViewTop: NSLayoutConstraint!
      var bannerViewLeft: NSLayoutConstraint!
      var bannerViewRight: NSLayoutConstraint!
      var banerDiscount: UIImageView!
      var bannerImageShop : UIImageView!
      var bannerTitle : UILabel!
      var bannerDescription: UILabel!
      var bannerButton: UIButton!
  
  
      override init (frame : CGRect) {
          super.init(frame : frame)
          self.bannerTitle.text = ""
  
      }
  
      convenience init () {
          self.init(frame:CGRect.zero)
      }
  
      required init(coder aDecoder: NSCoder) {
          fatalError("This class does not support NSCoding")
      }
  }
  </code></pre>
  
  <p>I'm instantiating this way:</p>
  
  <pre><code>var mainView : customShop = customShop()
  mainView.bannerTitle.text = "hola"
  let desc = super.getLanguageFromDict(self.areaDetailValues.texts_description)
  </code></pre>
  
  <p>As you can see in the image, it crashes always when I try to set any value. How this can be?</p>
  
  <p><a href="https://i.stack.imgur.com/Dwalj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Dwalj.png" alt="enter image description here"></a></p>