我正在使用核心数据。但当我 select 单元格进行编辑和删除操作时，数据序列未维护（在 table 视图上）

Question

我正在使用核心数据。但是当我 select 单元格进行编辑和删除操作时，数据序列未维护（在 table 视图上运行时间）.. 添加新数据后，我的数据随机存储在 table 而不维护实际序列（如果我在 selecting 任何特定单元格之前添加数据，则序列将被维护）。

import UIKit

class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    
    let tableView : UITableView = {
        let table = UITableView()
        table.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
        return table
    }()
    
    private var models = [ToDoListItem]()
    override func viewDidLoad() {
        super.viewDidLoad()
        getAllItems()

        // Do any additional setup after loading the view.
        title = "To Do List"
        view.addSubview(tableView)
        tableView.delegate = self
        tableView.dataSource = self
        tableView.frame = view.bounds
        navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(didTapAdd))
    }
    @objc private func didTapAdd(){
        let alert = UIAlertController(title: "New Item", message: "Enter New Item", preferredStyle: .alert)
        alert.addTextField(configurationHandler: nil)
        alert.addAction(UIAlertAction(title: "Submit", style: .cancel, handler: {[weak self] _ in
            guard let field = alert.textFields?.first, let text = field.text, !text.isEmpty else {
                return
            }
            self?.createItem(name: text)
        }))
        present(alert, animated: true)
    }
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return models.count
    }
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let model = models[indexPath.row]
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        cell.textLabel?.text = model.name
        return cell
    }
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath, animated: true)
        let item = models[indexPath.row]
        let sheet = UIAlertController(title: "Edit", message: nil, preferredStyle: .actionSheet)
        sheet.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        sheet.addAction(UIAlertAction(title: "Edit", style: .default, handler: {_ in
            
            let alert = UIAlertController(title: "Edit Item", message: "Edit your Item", preferredStyle: .alert)
            alert.addTextField(configurationHandler: nil)
            
            alert.textFields?.first?.text = item.name
            alert.addAction(UIAlertAction(title: "Save", style: .cancel, handler: {[weak self] _ in
                guard let field = alert.textFields?.first, let newName = field.text, !newName.isEmpty else {
                    return
                }
                self?.updateItem(item: item, newName: newName)
            }))
            self.present(alert, animated: true)
        }))
        sheet.addAction(UIAlertAction(title: "Delete", style: .destructive, handler: {[weak self] _ in
            self?.deleteItm(item: item)
        }))
        present(sheet, animated: true)
    }
    
    
    // core data
    func getAllItems(){
        do {
        models = try context.fetch(ToDoListItem.fetchRequest())
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        } catch {
        }
    }
    func createItem(name: String){
        let newItem = ToDoListItem(context: context)
        newItem.name = name
        newItem.createdAt = Date()
        do{
            getAllItems()
            try context.save()
        }catch{
        }
    }
    func deleteItm(item: ToDoListItem){
        context.delete(item)
        do{
            try context.save()
            getAllItems()
        }catch {
        }
    }
    func updateItem(item: ToDoListItem, newName: String){
        item.name = newName
        do{
            try context.save()
            getAllItems()
        }catch{
        }
    }
}

Answer 1

让我们休息一下：

models = try context.fetch(ToDoListItem.fetchRequest())

进入：

let request = ToDoListItem.fetchRequest()
models = try context.fetch(request)

现在，request 没有排序顺序。如果您添加排序，您将保证您的项目的顺序。

这取决于您要对它们进行排序的属性，但是：

fetchRequest.sortDescriptors = [NSSortDescriptor(key: #keyPath(ToDoListItem.name), ascending: true)]

或

fetchRequest.sortDescriptors = [NSSortDescriptor(key: #keyPath(ToDoListItem.createdAt), ascending: true)]

可能是一个解决方案。

我正在使用核心数据。但当我 select 单元格进行编辑和删除操作时，数据序列未维护（在 table 视图上）

I am using core data. but sequence of data is not maintained (on table view) when I select cell for edit and delete action

core-data

ios

swift