如何在关闭时将UIToolBar固定在键盘顶部

// 监听键盘打开和关闭事件
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: UIResponder.keyboardWillHideNotification, object: nil)

// 键盘打开时的处理方法
@objc func keyboardWillShow(_ notification: Notification) {
    if let keyboardFrame = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect {
        let toolbarHeight: CGFloat = 44.0 // 自定义UIToolBar的高度
        let toolbarFrame = CGRect(x: 0, y: keyboardFrame.origin.y - toolbarHeight, width: UIScreen.main.bounds.width, height: toolbarHeight)
        
        let toolbar = UIToolbar(frame: toolbarFrame)
        // 设置UIToolBar的样式、按钮等
        
        self.view.addSubview(toolbar)
    }
}

// 键盘关闭时的处理方法
@objc func keyboardWillHide(_ notification: Notification) {
    if let toolbar = self.view.subviews.first(where: { $0 is UIToolbar }) {
        toolbar.removeFromSuperview()
    }
}