如何在轻触按钮时撤消表格视图单元格的重新排序

class MyTableViewController: UITableViewController {
    var dataSource = ["Item 1", "Item 2", "Item 3", "Item 4"]
    var originalOrder: [Int]?

    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.isEditing = true
        originalOrder = dataSource.enumerated().map { $0.offset }
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return dataSource.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        cell.textLabel?.text = dataSource[indexPath.row]
        return cell
    }

    func undoReordering() {
        dataSource = originalOrder!.map { index in dataSource[index] }
        tableView.reloadData()
    }

    @IBAction func undoButtonTapped(_ sender: UIButton) {
        undoReordering()
    }
}