使用带委托协议的Tableview从视图控制器B传递数据到视图控制器A

protocol TableViewDelegate: class {
    func didSelectItem(item: String)
}

class ViewControllerB: UIViewController, UITableViewDelegate {
    weak var delegate: TableViewDelegate?
    
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let selectedItem = data[indexPath.row]
        delegate?.didSelectItem(item: selectedItem)
    }
}

class ViewControllerA: UIViewController, TableViewDelegate {
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let viewControllerB = segue.destination as? ViewControllerB {
            viewControllerB.delegate = self
        }
    }
    
    func didSelectItem(item: String) {
        // 在这里处理从视图控制器B传递过来的数据
    }
}