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
    }