//注册点击事件
        self.view.addGestureRecognizer(UITapGestureRecognizer(target:self, action:#selector(你的viewcontroller.handleTap(sender:))))
//对应方法
func handleTap(sender: UITapGestureRecognizer) {
        if sender.state == .ended {
            你的textfield.resignFirstResponder()
        }
        sender.cancelsTouchesInView =false
    }