##Usage ###More details you can find in the project sample ###CircleTransitonButton is a SubClass of UIButton
let btn = CircleTransitonButton(frame: CGRect(x: 100, y: 100, width: 100, height: 50))
btn.backgroundColor = UIColor.black
btn.presentedViewController = secondVC
btn.delegate = self
UIViewController should observer CircleTransitionButtonDelegate
class FirstViewController: UIViewController, CircleTransitionButtonDelegate