Avoid button targets in Swift 2.2

button.swift

class Button : UIButton {
    private var _action : (()->())?
    var action : ()->() {
        get {
            return _action!
        }
        set (newAction) {
            _action = newAction
            self.addTarget(self,
                           action: #selector(Button.actionCaller),
                           forControlEvents: UIControlEvents.TouchUpInside)
        }
    }
    
    @objc func actionCaller() {
        self._action!()
    }
}