当键盘显示时更改自动布局常量

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: UIResponder.keyboardWillHideNotification, object: nil)

@objc func keyboardWillShow(_ notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        // 根据键盘高度调整布局常量
        // 例如，将底部约束的constant设置为键盘高度
        bottomConstraint.constant = keyboardSize.height
        UIView.animate(withDuration: 0.3) {
            self.view.layoutIfNeeded()
        }
    }
}

@objc func keyboardWillHide(_ notification: Notification) {
    // 恢复布局常量到原始状态
    bottomConstraint.constant = 0
    UIView.animate(withDuration: 0.3) {
        self.view.layoutIfNeeded()
    }
}