title: Unable to interpret '|' character
body: <p>I need your help because I dont understand what's going on with my auto constraints. The constraints of my switch make the app crash. When I remove them it work nicely.
  This is the error message that I get:
  Unable to interpret '|' character, because the related view doesn't have a superview 
  H:|-100-[v0(35)]| </p>
  
  <p>thx for your help</p>
  
  <p>Here is my code :</p>
  
  <pre><code>class selectionCustomCell: UITableViewCell{
      var label: UILabel = {
          let attribution = UILabel()
          attribution.text = "Nom du label"
          attribution.textColor = UIColor(r: 0, g: 185, b: 255)
          attribution.lineBreakMode = NSLineBreakMode.ByWordWrapping
          attribution.numberOfLines = 0
          attribution.translatesAutoresizingMaskIntoConstraints = false
          return attribution
      }()
  
    var switchElement: UISwitch{
          let sL = UISwitch()
          sL.setOn(true, animated: true)
          sL.onTintColor = UIColor(r: 0, g: 185, b: 255)
          sL.tintColor = UIColor(r: 0, g: 185, b: 255)
          sL.translatesAutoresizingMaskIntoConstraints = false
          return sL
      }
  
      override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
          super.init(style: .Default, reuseIdentifier: reuseIdentifier)
          addSubview(switchElement)
          addSubview(label)
          setupViews()
      }
  
      func setupViews(){
          addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-20-[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": label]))          
          addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-20-[v0]", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": label]))
  
  
          addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-100-[v0(35)]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": switchElement]))
  
  
          addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-20-[v0(35)]", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": switchElement]))
  
  
      }
  
      required init?(coder aDecoder: NSCoder) {
          fatalError("init(coder:) has not been implemented")
      }
  
  }
  </code></pre>