当到期或CVV字段处于活动状态且卡号字段为空时，关闭键盘的Swift iOS条带-How

let tapGesture = UITapGestureRecognizer(target: self, action: #selector(dismissKeyboard))
view.addGestureRecognizer(tapGesture)

@objc func dismissKeyboard() {
    view.endEditing(true)
}

func textFieldDidBeginEditing(_ textField: UITextField) {
    if (textField == expirationTextField || textField == cvvTextField) && cardNumberTextField.text?.isEmpty == true {
        dismissKeyboard()
    }
}