在swift 4.2中将选中单元格的状态保存在表视图中

var selectedIndexPath: IndexPath?

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    selectedIndexPath = indexPath
}

func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
    selectedIndexPath = nil
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
    
    if let selectedIndexPath = selectedIndexPath, selectedIndexPath == indexPath {
        cell.accessoryType = .checkmark
    } else {
        cell.accessoryType = .none
    }
    
    return cell
}