Add Pass Button

AddPassButton.swift

private func setupAddPassButton() {
  let button = PKAddPassButton(style: .BlackOutline)
  button.addTarget(self, action: #selector(passTouchUpInside), forControlEvents: .TouchUpInside)
    
  button.translatesAutoresizingMaskIntoConstraints = false
  view.addSubview(button)
  button.centerXAnchor.constraintEqualToAnchor(view.centerXAnchor).active = true
  button.centerYAnchor.constraintEqualToAnchor(view.centerYAnchor).active = true
}