swift 创建button

        let btn  = UIButton()

        let rect = CGRect(x: 0, y: 0, width: 200, height: 49)

        btn.frame = rect

        btn.setTitle("登录", for: .normal)
        btn.setTitleColor(UIColor.darkGray, for: UIControlState.normal)
        btn.setImage(UIImage(named: "tabbar_compose_icon_add"), for: .normal)
        btn.setImage(UIImage(named: "tabbar_compose_icon_add_highlighted"), for:.highlighted)
        btn.setBackgroundImage(UIImage(named: "tabbar_compose_button"), for:.normal)
        btn.setBackgroundImage(UIImage(named: "tabbar_compose_button_highlighted"), for: .highlighted)

        btn.addTarget(self, action: #selector(VIewController.loginBtnClick), for: UIControlEvents.touchUpInside)

    //MARK:登录
    func loginBtnClick(){
        delegate?.loginBtnWillClick()
    }