ios - NSFetchedResultsController看不到插入(或更新)

我有一个非常基本的NSFetchedResultsController，它在UITableView中向用户显示数据，允许用户添加新实体等等。
但是，每当我添加新实体时，我的应用程序会崩溃（有时只是发出警告），并显示以下消息：

CoreData: error: Serious application error.  An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:.  Invalid update: invalid number of sections.  The number of sections contained in the table view after the update (3) must be equal to the number of sections contained in the table view before the update (2), plus or minus the number of sections inserted or deleted (0 inserted, 0 deleted). with userInfo (null)

注意，即使numberOfRows已经从2更新到3，插入/删除操作仍然显示(0 inserted, 0 deleted)。所以我最好的理解是NSFetchedResultsController没有注意到变化或其他什么。
我的NSFetchedResultsController代码是：

func fetch(frcToFetch: NSFetchedResultsController) {

    do {
        try frcToFetch.performFetch()
    } catch {
        return
    }
}

func fetchRequest() -> NSFetchRequest {

    // Initialize Fetch Request
    let fetchRequest = NSFetchRequest(entityName: "ItemInfo")

    // Add Sort Descriptors
    let nameSortDescriptor = NSSortDescriptor(key: "iName", ascending: true)
    fetchRequest.sortDescriptors = [nameSortDescriptor]

    return fetchRequest
}


func getFRC() -> NSFetchedResultsController {

    if let context = self.context{
        fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest(), managedObjectContext: context, sectionNameKeyPath: "iName.stringGroupByFirstInitial", cacheName: nil)
        fetchedResultsController.delegate = self
    }
    return fetchedResultsController
}

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 {
            let cell = tableView.cellForRowAtIndexPath(indexPath)! as UITableViewCell
            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;
    }
}

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    if let sections = fetchedResultsController.sections {
        return sections.count
    }

    return 0
}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    if let sections = fetchedResultsController.sections {
        let sectionInfo = sections[section]
        return sectionInfo.numberOfObjects
    }

    return 0
}

插入新记录的代码是：

let entity: NSEntityDescription.entityForName("ItemInfo", inManagedObjectContext: self.context!)!

let record = NSManagedObject(entity: entity, insertIntoManagedObjectContext: self.context!)

record.setValue(name, forKey: "iName")
record.setValue(self.billingMode.text, forKey: "iBillingMode")

do {
            // Save Record
            try record.managedObjectContext?.save()
            try self.context!.save()
            // Dismiss View Controller
            dismissViewControllerAnimated(true, completion: nil)

        } catch {
            let saveError = error as NSError
            print("\(saveError), \(saveError.userInfo)")

            // Show Alert View
            showAlertWithTitle("Unexpected Error", message: "Your data could not be saved. Please try again later.", cancelButtonTitle: "Done")
        }

请注意，self.context变量是从具有NSFetchedResultsController的实际或主视图控制器传递的。

最佳答案

请注意，问题在于节数而不是行数。你需要实施：

(void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo

关于ios - NSFetchedResultsController看不到插入(或更新)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/36514273/