UIButton 添加支持Block点击事件的功能

extension UIButton {
    // 定义关联的Key
    private struct AssociatedKeys {
        static var actionKey = "UIButton+Extension+ActionKey"
    }
    func addActionWithBlock(_ closure: @escaping (_ sender: UIButton) -> Void,
                            for controlEvents: UIControl.Event = .touchUpInside) {
        //把闭包作为一个值 先保存起来
        objc_setAssociatedObject(self, &AssociatedKeys.actionKey, closure, objc_AssociationPolicy.OBJC_ASSOCIATION_COPY)
        //给按钮添加传统的点击事件，调用写好的方法
        self.addTarget(self, action: #selector(my_ActionForTapGesture), for: controlEvents)
    }
    @objc private func my_ActionForTapGesture() {
        //获取闭包值
        let obj = objc_getAssociatedObject(self, &AssociatedKeys.actionKey)
        if let action = obj as? (_ sender:UIButton)->() {
            //调用闭包
            action(self)
        }
    }
}