超出视图外控件的点击事件

设置父视图的clipsToBounds属性为true，子视图允许超出父视图布局，这时的子视图是无法点击的

子视图超出父视图

父视图重写hitTest方法，可以将事件传递到子视图

 /// 超出视图外按钮的点击事件处理
    ///
    /// - Parameters:
    ///   - point: 点击的点
    ///   - event: 事件
    /// - Returns: 返回的按钮
    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        var view = super.hitTest(point, with: event)
        if view == nil {
            for subView in self.subviews {
                let p = subView.convert(point, from: self)
                if subView.bounds.contains(p) {
                    view = subView
                } 
            }
        }
        return view
    }