Gesture和UIControl触发顺序

2017-05-20

UIControl的事件不触发

今天发现一个自定义的UIControl控件的事件无法触发，查了以下发现原因是

UIControl被置于一个有TapGestureRecognizer的SuperView上 根据搜索这个问题2010年时在UIButton上也存在写了一段Demo测试了一下

UIButton被Apple处理过了

经过Demo测试发现，在一个存在TapGesture的View上，UIButton的TouchUpInside可以正确被触发，但是自定义的UIControl不行

具体原因猜测是因为GestureRecognizer会取消掉Touch的生命周期，看来在苹果的底层传递机制上，是先进行Gesture的遍历，才会去对Touch做处理

在SuperView识别到了Gesture后，UITouch的传递就会被取消掉，导致子View无法触发Tracking事件

Demo

public class GestureSuperView: UIView {
    let control: UIControl = UIControl()
    let button: UIButton = UIButton()

    convenience public init(size: CGSize) {
        self.init(frame: CGRect(origin: CGPoint.zero, size: size))
        self.backgroundColor = UIColor.red
        self.addSubview(control)
        self.addSubview(button)

        let tap: UITapGestureRecognizer =  UITapGestureRecognizer(target: self, action: #selector(tapGestureProcess(tap:)))
        //-----------------------------------
//        tap.cancelsTouchesInView = false
        //-----------------------------------
        self.addGestureRecognizer(tap)

        control.frame = CGRect(x: 0, y: 0, width: self.bounds.width/2, height: self.bounds.height)
        control.addTarget(self, action: #selector(touchUpInside(control:)), for: .touchUpInside)
        control.backgroundColor = UIColor.blue

        button.frame = CGRect(x: self.bounds.width/2, y: 0, width: self.bounds.width/2, height: self.bounds.height)
        button.addTarget(self, action: #selector(touchUpInside(control:)), for: .touchUpInside)
        button.backgroundColor = UIColor.yellow

    }

    @objc func tapGestureProcess(tap: UITapGestureRecognizer) {
        print("Invoke Tap Gesture...")
    }

    @objc func touchUpInside(control: UIControl) {
        print("Invoke Touch Up Inside...")
    }

}