ios - 如何使用后退按钮更新 tableviewcell？

Question

我有这个 tableviewcontroller 和 detailviewcontroller，它有一个文本字段，当用户单击 tableviewcell 时，它会转到文本字段，用户可以编辑内容!!我应该如何通过后退按钮用文本字段中的新内容更新表格 View ？

let sectionTitles = ["ongoing","Done"]
var list = [String]()

class MasterViewController: UITableViewController {

    var detailViewController: DetailViewController? = nil
    var objects = sectionTitles.map({_ in return [Any]()})

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        navigationItem.leftBarButtonItem = editButtonItem

        let addButton = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(insertNewObject(_:)))
        navigationItem.rightBarButtonItem = addButton

        if let split = splitViewController {
            let controllers = split.viewControllers
            detailViewController = (controllers[controllers.count-1] as! UINavigationController).topViewController as? DetailViewController
        }
    }

    @objc
    func insertNewObject(_ sender: Any) {
        objects[0].insert("Task 1", at: 0)
        let indexPath = IndexPath(row: 0, section: 0)
        tableView.insertRows(at: [indexPath], with: .automatic)
    }

    // MARK: - Segues

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "showDetail" {
            if let indexPath = tableView.indexPathForSelectedRow {
                let object = objects[indexPath.section][indexPath.row] as! String
                let controller = (segue.destination as! UINavigationController).topViewController as! DetailViewController
                controller.detailItem = object

                controller.navigationItem.leftBarButtonItem = splitViewController?.displayModeButtonItem
                controller.navigationItem.leftItemsSupplementBackButton = true
            }
        }
    }
}

class DetailViewController: UIViewController,UINavigationControllerDelegate {

    @IBOutlet weak var detailDescription: UITextField!

    func configureView() {

        // Update the user interface for the detail item.
        if let detail = detailItem {

            if let label = detailDescription {
                label.text = detail.description
                list.append(label.text!)
            }
        }
    }
}

Answer 1

我建议使用回调闭包来更新模型并重新加载行。回调在 viewDidDisappear 中调用。闭包中的代码检查值是否不同并更新模型并在必要时重新加载行。

• 在 DetailViewController 中创建回调

  var callback : ((String)->())?
  

  • 在 viewDidDisappear 中调用回调(或者可能已经在 viewWillDisappear 中)

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        callback?(detailDescription.text!)
    }
    

• 在 MasterViewController 中添加闭包 prepare(for

  override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
      if segue.identifier == "showDetail" {
          if let indexPath = tableView.indexPathForSelectedRow {
              let object = objects[indexPath.section][indexPath.row] as! String
              let controller = (segue.destination as! UINavigationController).topViewController as! DetailViewController
              controller.detailItem = object
              controller.callback = { newValue in 
                 if object != newValue {
                     self.objects[indexPath.section][indexPath.row] = newValue
                     self.tableView.reloadRows(at: [indexPath], with: .automatic)
                  }
              }
              controller.navigationItem.leftBarButtonItem = splitViewController?.displayModeButtonItem
              controller.navigationItem.leftItemsSupplementBackButton = true
          }
      }
  }