NSFetchedResultsController没有看到插入（或更新）

Question

我有一个非常基本的NSFetchedResultsController，向用户显示数据UITableView，允许用户添加一个新的实体等等。

但是，每当我添加了一个新的实体，我的应用程序崩溃（或有时只是警告）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，甚至认为numberOfRows已经从2更新到3，插入/删除东西仍然说(0 inserted, 0 deleted)。所以我最好的理解是，NSFetchedResultsController没有注意到变化或什么。

我对NSFetchedResultsController代码：

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 
} 

并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") 
     } 

注意，self.context变量是从具有实际或主视图控制器通过NSFetchedResultsController。

Answer 1

请注意，问题是段段的数量不是段的行数。您需要实施：

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