ios swift slider滑动监听

override func viewDidLoad() {           
        slider.addTarget(self, action:#selector(sliderValurChanged(_:for:)), for: .valueChanged)
}
 / /slider滑动监听
 @objc func sliderValurChanged(_ slider: UISlider?, for event: UIEvent?) {
        let touchEvent = event?.allTouches?.first
        switch touchEvent?.phase {
        case .began:
            print("开始拖动")
        case .moved:
            print(slider?.value as Any)
        case .ended:
            print("结束拖动")
        default:
            break
        }
    }