toolbar - 如何从 UITableView 小键盘工具栏中添加的向上、向下箭头遍历单元格？

Question

 numberToolbar.items=[
            UIBarButtonItem(image:UIImage(named: "icKeyboardArrowUp"), style: UIBarButtonItem.Style.plain, target: self, action: #selector(ViewController.traverseUp)),
            UIBarButtonItem(image:UIImage(named: "icKeyboardArrowDown") , style: UIBarButtonItem.Style.plain, target: self, action: #selector(ViewController.traverseDown)),
            UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.flexibleSpace, target: self, action: nil),
            UIBarButtonItem(title: "Done", style: UIBarButtonItem.Style.plain, target: self, action: #selector(ViewController.donePressed))
        ]

        numberToolbar.sizeToFit()