如何在核心数据中移动行 – 使用Faulting教程 – IOS

我使用这个教程Faulting来创build列表的列表

现在我想在列表视图控制器中移动行。

它成功移动行，但我不能保存这些更改

我经历了很多解决scheme无济于事。

请帮帮我

import UIKit import CoreData class ListViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, NSFetchedResultsControllerDelegate { let ReuseIdentifierItemCell = "ItemCell" @IBOutlet weak var tableView: UITableView! var list: List! var managedObjectContext: NSManagedObjectContext { get { return list.managedObjectContext! } } lazy var fetchedResultsController: NSFetchedResultsController = { // Initialize Fetch Request let fetchRequest = NSFetchRequest(entityName: "Item") // Add Sort Descriptors let sortDescriptor = NSSortDescriptor(key: "name", ascending: true) fetchRequest.sortDescriptors = [sortDescriptor] // Predicate let predicate = NSPredicate(format: "%K == %@", "list", self.list) fetchRequest.predicate = predicate // Initialize Fetched Results Controller let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext, sectionNameKeyPath: nil, cacheName: nil) // Configure Fetched Results Controller fetchedResultsController.delegate = self return fetchedResultsController }() // MARK: - // MARK: View Life Cycle override func viewDidLoad() { super.viewDidLoad() do { try self.fetchedResultsController.performFetch() } catch { let fetchError = error as NSError print("\(fetchError), \(fetchError.userInfo)") } } // MARK: - // MARK: Table View Data Source Methods func numberOfSectionsInTableView(tableView: UITableView) -> Int { if let sections = fetchedResultsController.sections { return sections.count } return 0 } func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int { if let sections = fetchedResultsController.sections { let sectionInfo = sections[section] return sectionInfo.numberOfObjects } return 0 } func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCellWithIdentifier(ReuseIdentifierItemCell, forIndexPath: indexPath) // Configure Table View Cell configureCell(cell, atIndexPath: indexPath) return cell } func configureCell(cell: UITableViewCell, atIndexPath indexPath: NSIndexPath) { // Fetch Item let item = fetchedResultsController.objectAtIndexPath(indexPath) as! Item // Update Cell cell.textLabel!.text = item.name } func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool { return true } func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) { if (editingStyle == .Delete) { // Fetch Item let item = fetchedResultsController.objectAtIndexPath(indexPath) as! Item // Delete Item self.managedObjectContext.deleteObject(item) } } // MARK: - // MARK: Table View Delegate Methods func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) { tableView.deselectRowAtIndexPath(indexPath, animated: true) } // MARK: - // MARK: Fetched Results Controller Delegate Methods func controllerWillChangeContent(controller: NSFetchedResultsController) { tableView.beginUpdates() } func controllerDidChangeContent(controller: NSFetchedResultsController) { tableView.endUpdates() } func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) { switch (type) { case .Insert: if let indexPath = newIndexPath { tableView.insertRowsAtIndexPaths([indexPath], withRowAnimation: .Fade) } break; case .Delete: if let indexPath = indexPath { tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade) } break; case .Update: if let indexPath = indexPath { if let cell = tableView.cellForRowAtIndexPath(indexPath) { configureCell(cell, atIndexPath: indexPath) } } break; case .Move: if let indexPath = indexPath { tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade) } if let newIndexPath = newIndexPath { tableView.insertRowsAtIndexPaths([newIndexPath], withRowAnimation: .Fade) } break; } } // MARK: - // MARK: Actions @IBAction func addItem(sender: UIBarButtonItem) { let entityDescription = NSEntityDescription.entityForName("Item", inManagedObjectContext: self.managedObjectContext) // Initialize Item let item = Item(entity: entityDescription!, insertIntoManagedObjectContext: self.managedObjectContext) // Configure Item item.list = self.list item.name = "\(list.name!) - Item \(numberOfItems())" // Save Changes do { try self.managedObjectContext.save() } catch { let saveError = error as NSError print("\(saveError), \(saveError.userInfo)") } } // MARK: - // MARK: Helper Methods private func numberOfItems() -> Int { var result = 0 if let items = self.fetchedResultsController.fetchedObjects { result = items.count } return result } } 

谢谢

Answer 1

好吧，我们去错了之后修改了这段代码：

之前：

  let sortDescriptor = NSSortDescriptor(key: "position", ascending: true) 

后：

  let sortDescriptor = NSSortDescriptor(key: "position", ascending: false) 

感谢所有