当创建自定义view时，如果底层view与上层view（button）都需要处理点击事件时：
继承UIGestureRecognizerDelegate，设置底层view的UITapGestureRecognizer的delegate为self，实现shouldReceive的方法
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
if (touch.view?.isKind(of: self.classForCoder))! {
return true
}else{
return false
}
}
