Question

CoreData：错误：严重的应用程序错误。在调用-controllerDidChangeContent：期间，从NSFetchedResultsController的委托中捕获到异常。尝试在使用userInfo（null）

更新之前从第0部分删除第1行，该第1行只包含1行

在我的应用中 - 我有一个表视图。表视图有两个部分。该部分是使用核心数据实体中的瞬态属性来确定的，如下所示 -

@objc var section: String?{
   return event < Date() ? "before" : "after"
}

该应用应该像这样工作：

表格视图控制器允许使用单元格滑动删除/取消。当从触发委托方法的fetchedResults控制器中删除某个项目时，我会删除 performBatchUpdates 中的项目。这适用于插入和删除。
当用户选择一行时，它会转移到集合视图。视图在collectionView中滚动到所选项目（项目跨越整个视图）。用户可以在各种单元项之间来回滚动。可以从集合视图中删除项目。我也在这里使用 performBatchUpdates 来删除委托方法中的项目。这也很好。
问题发生在我从集合视图转换回表View后，只有当我碰巧删除集合View中的项目并返回tableView时才会出现问题。

a）如果我插入项目 - 没问题。

b）如果我从与我在集合视图中删除项的部分相同的部分删除行。它可以正常工作。

c）上述错误仅在我尝试从其他部分（第0或第1部分）删除某个项目时显示，即我在collectionView中未删除的部分。

示例 - 在表视图中

**第0节**

项目A
项目B

第1节

项目C. 项目D

如果我在收藏视图中删除项目A ，然后返回到表格视图，我会看到以下内容（这是正确的）

删除后的表格视图：

第0节

项目B

第1节

项目C. 项目D

但是当我尝试删除项目D或项目C.控制器认为我试图删除第0部分中的项目！

但如果我在第0部分中首先删除了项目B，则没有问题。

如果在删除第0部分中的项目B后删除第1部分中的项目C和D - 没有问题。

我尝试通过在从核心数据（获取结果控制器）删除时打印indexPaths，并在触发时在didChangeObject，didChangeSection等中打印。它会打印我正在尝试删除的正确行和部分。我正在努力解决这个问题。有没有人遇到类似问题并有解决方案？

我的tableViewController

var deleteMode:Bool = false

lazy var fetchedResultsController:NSFetchedResultsController = { () -> NSFetchedResultsController<Event> in
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Event")
    request.sortDescriptors = [NSSortDescriptor(key:"eventDate",ascending:false)]
    //request.predicate = NSPredicate(format:"contact.name = %@", self.)
    let appDelegate = UIApplication.shared.delegate as? AppDelegate
    let managedObjectContext = appDelegate?.persistentContainer.viewContext
    let fetchedResultsController = NSFetchedResultsController(fetchRequest: request, managedObjectContext: managedObjectContext!, sectionNameKeyPath:"section", cacheName: nil)
    fetchedResultsController.delegate = self
    return fetchedResultsController as! NSFetchedResultsController<Event>
}()

viewDidLoad

tableViewController：

override func viewDidLoad() {
    super.viewDidLoad()

    //Load data
    do{
        try fetchedResultsController.performFetch()
    }catch let error{
        print("\(String(describing: Bundle.main.bundleIdentifier)):\(error)")
    }

    // Other code
}

 @IBAction func unwindToEvents(segue: UIStoryboardSegue){
    do{
        try self.fetchedResultsController.performFetch()

    }catch let error{
        print("\(String(describing: Bundle.main.bundleIdentifier)):\(error)")
    }
    eventsTableView.reloadData()
}

NSFetched结果控制器和tableView委托方法

 func numberOfSections(in tableView: UITableView) -> Int {

    let count = fetchedResultsController.sections?.count ?? 0

   // some other code...

    return count
}//end of numberOfSections

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        guard let count = fetchedResultsController.sections?[section].numberOfObjects else{
            return 0
        }
        return count
    }
}//end of numberOfRowsInSection

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let eventCell = eventsTableView.dequeueReusableCell(withIdentifier: storyBoard.eventCell, for: indexPath) as! EventTableViewCell
        eventCell.event = fetchedResultsController.object(at: indexPath) as Event
        return eventCell
    }
}//end of cellForRowAt

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        self.currentEventIndex = indexPath
        let event = fetchedResultsController.object(at: indexPath)
        performSegue(withIdentifier: storyBoard.showEventDetail, sender: event)
    }
}//end of tableView didSelectRowAt


func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
        let delete = UITableViewRowAction(style: .destructive, title: "Delete") { (action, indexPath) in
            // delete item at indexPath
            let event = self.fetchedResultsController.object(at: indexPath)
            self.fetchedResultsController.managedObjectContext.delete(event)
            do{
                self.deleteMode = true
                try self.fetchedResultsController.managedObjectContext.save()
            }catch let error as NSError{
                 print(error.localizedDescription)
            }
        }
        let cancel = UITableViewRowAction(style: .normal, title: "Cancel") { (action, indexPath) in
            //cancel swipe action
        }
        cancel.backgroundColor = UIColor.blue

        return [delete,cancel]
}//end of editActionsForRowAt


func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
        return true
}//end of canEditRowAt


func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        guard let sectionInfo = self.fetchedResultsController.sections?[section] else {
            return " "
        }
        return sectionInfo.name //which will be the sectionNameKeyPath we provided earlier.
    }


//MARK: NSFecthedResultscontroller delegate methods

func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange sectionInfo: NSFetchedResultsSectionInfo, atSectionIndex sectionIndex: Int, for type: NSFetchedResultsChangeType) {

    switch type{
    case NSFetchedResultsChangeType.delete:
        let sectionIndexSet = NSIndexSet(index:sectionIndex) as IndexSet
     blockOps.append(BlockOperation(block:{
            self.eventsTableView.deleteSections(sectionIndexSet, with: .automatic)
        }))
    default:
        break
    }
}

func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
        switch type{
        case .delete:
            print(indexPath!.row,indexPath!.section)
            blockOps.append(BlockOperation(block:{
                self.eventsTableView.deleteRows(at: [indexPath!], with: .automatic)
            }))
        default:
            break
        }
}//end of didChange anObject at

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
    if self.deleteMode{//perform block op only for delete mode
        self.deleteMode = false
        eventsTableView.performBatchUpdates({
            for operation in blockOps{
                operation.start()
            }
        },completion: { (completion) in

        })
    }
}//end of controllerDidChangeContent

}//end of EventsViewController

集合视图：

var blockOps = [BlockOperation]()

lazy var fetchedResultsController:NSFetchedResultsController = { () -> NSFetchedResultsController<Event> in
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Event")
    request.sortDescriptors = [NSSortDescriptor(key:"eventDate",ascending:false)]
    let appDelegate = UIApplication.shared.delegate as? AppDelegate
    let managedObjectContext = appDelegate?.persistentContainer.viewContext
    let fetchedResultsController = NSFetchedResultsController(fetchRequest: request, managedObjectContext: managedObjectContext!, sectionNameKeyPath: "section", cacheName: nil)
    fetchedResultsController.delegate = self
    return fetchedResultsController as! NSFetchedResultsController<Event>
}()

//Other code .........

@IBAction func didTapDeleteEvent(_ sender: UIButton) {
    let currentItemIndex =  eventDetailCollection.indexPathsForVisibleItems.first
    if let indexPath = currentItemIndex{
        let event = self.fetchedResultsController.object(at: indexPath)

        self.fetchedResultsController.managedObjectContext.delete(event)
        do{
            self.deleteMode = true
            try self.fetchedResultsController.managedObjectContext.save()
        }catch let error as NSError{
           print(error.localizedDescription)
        }
    }
}//end of didTapDelete



//The delegate methods

func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
    switch type{
    case .delete:
        blockOps.append(BlockOperation(block:{
            self.eventDetailCollection.deleteItems(at: [indexPath!])
        }))
    default:
        break
    }
}//end of didChange anObject at

func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange sectionInfo: NSFetchedResultsSectionInfo, atSectionIndex sectionIndex: Int, for type: NSFetchedResultsChangeType) {
    switch type{
    case NSFetchedResultsChangeType.delete:
        let sectionIndexSet = NSIndexSet(index:sectionIndex) as IndexSet
        blockOps.append(BlockOperation(block:{
            self.eventDetailCollection.deleteSections(sectionIndexSet)
        }))
    default:
        break
    }
}//end didChange SectionInfo

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
    if self.deleteMode{//perform block op only in delete mode
        self.deleteMode = false
        eventDetailCollection.performBatchUpdates({
            for operation in blockOps{
                operation.start()
            }
        },completion: { (completion) in
            if let count = self.fetchedResultsController.fetchedObjects?.count {
                if count < 1{
                    self.performSegue(withIdentifier: "detailToEvents", sender: self)
                }
            }
        })
    }
}//end of controllerDidChangeContent

Answer 1

我的代码中遇到了同样的问题。我仍然是编程和Swift的新手，但这里是我用于从tableview中滑动删除的代码。也许这可以帮助你的代码。

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {

    guard editingStyle == .delete else {
        return
    }

    // Fetch
    let inventory = fetchedResultsController.object(at: indexPath)

    // MARK: Delete
    // tells managed object cotext to delete the selected object
    fetchedResultsController.managedObjectContext.delete(inventory)

    // goes to the data store and performs the action
    try? fetchedResultsController.managedObjectContext.save()

    // refetches the new data store
    try? fetchedResultsController.performFetch()

    // reloads data to the tableview
    tableView.reloadData()
}

Swift核心数据：在调用-controllerDidChangeContent

示例 - 在表视图中

删除后的表格视图：

1 个答案: