Question

我堆叠了这个错误：

CoreData：错误：严重的应用程序错误。抓住了一个例外在调用期间来自NSFetchedResultsController的委托 -controllerDidChangeContent :.尝试从第0部分删除第0行，但在使用userInfo（null）
进行更新之前只有0部分

我不知道是谁调用删除操作 - 说实话，我在整个项目中没有任何删除操作。任何想法如何调试这种情况？

public func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
    switch(type) {
    case .insert:
        self.operation.append(BlockOperation(block: {
                                                        self.tableView?.insertRows(at: [newIndexPath!], with: .bottom)
                                                    })
        )
        // self.tableView?.scrollToRow(at: newIndexPath, at: .bottom, animated: true)
        break
    case .update:
        self.operation.append(BlockOperation(block: {
                                                        self.tableView?.reloadRows(at: [indexPath!], with: .bottom)
                                                    })
        )
        break
    default:
        break
    }
}

public func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
    self.tableView?.beginUpdates()
    for o in self.operation {
        o.start()
    }
    self.tableView?.endUpdates()

}

提前致谢。

更新1

override public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell: ChannelTableCell = tableView.dequeueReusableCell(withIdentifier: "ChannelTableCell", for: indexPath) as! ChannelTableCell
    cell.setChannel(self.channelController.object(at: indexPath), delegate: self)

    return cell
}

更新2

我已经简化了didChange方法，现在在reloadRows（）调用时得到错误。

public func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
    switch(type) {
    case .insert:
        self.tableView?.insertRows(at: [newIndexPath!], with: .bottom)
        break;
    case .update:
        self.tableView?.reloadRows(at: [indexPath!], with: .bottom)
        break
    default:
        break
    }
}

堆栈

*** First throw call stack:
(
    0   CoreFoundation                      0x0000000109db2d4b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x00000001089cb21e objc_exception_throw + 48
    2   CoreFoundation                      0x0000000109db6e42 +[NSException raise:format:arguments:] + 98
    3   Foundation                          0x000000010856066d -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 195
    4   UIKit                               0x000000010ab1ab60 -[UITableView _endCellAnimationsWithContext:] + 6265
    5   UIKit                               0x000000010ab34f62 -[UITableView _updateRowsAtIndexPaths:updateAction:withRowAnimation:] + 331
    6   Joker                               0x00000001080335ac _TFC5Joker17AirViewController10controllerfTGCSo26NSFetchedResultsControllerPSo20NSFetchRequestResult__9didChangeP_2atGSqV10Foundation9IndexPath_3forOSC26NSFetchedResultsChangeType12newIndexPathGSqS4___T_ + 860
    7   Joker                               0x0000000108033740 _TToFC5Joker17AirViewController10controllerfTGCSo26NSFetchedResultsControllerPSo20NSFetchRequestResult__9didChangeP_2atGSqV10Foundation9IndexPath_3forOSC26NSFetchedResultsChangeType12newIndexPathGSqS4___T_ + 256
    8   CoreData                            0x0000000109a25400 __82-[NSFetchedResultsController(PrivateMethods) _core_managedObjectContextDidChange:]_block_invoke + 6608
    9   CoreData                            0x00000001098fa9a7 developerSubmittedBlockToNSManagedObjectContextPerform + 199
    10  CoreData                            0x00000001098fa85f -[NSManagedObjectContext performBlockAndWait:] + 255
    11  CoreData                            0x0000000109a23a17 -[NSFetchedResultsController(PrivateMethods) _core_managedObjectContextDidChange:] + 119
    12  CoreFoundation                      0x0000000109d505ec __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12
    13  CoreFoundation                      0x0000000109d504eb _CFXRegistrationPost + 427
    14  CoreFoundation                      0x0000000109d50252 ___CFXNotificationPost_block_invoke + 50
    15  CoreFoundation                      0x0000000109d13282 -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 2018
    16  CoreFoundation                      0x0000000109d1231b _CFXNotificationPost + 667
    17  Foundation                          0x000000010849181b -[NSNotificationCenter postNotificationName:object:userInfo:] + 66
    18  CoreData                            0x00000001098e2d90 -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] + 704
    19  CoreData                            0x0000000109979a91 -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:deletions:updates:refreshes:deferrals:wasMerge:] + 1713
    20  CoreData                            0x00000001098dcb32 -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] + 3554
    21  CoreData                            0x00000001098b5764 -[NSManagedObjectContext executeFetchRequest:error:] + 420
    22  libswiftCoreData.dylib              0x000000010c769e78 _TFE8CoreDataCSo22NSManagedObjectContext5fetchuRxSo20NSFetchRequestResultrfzGCSo14NSFetchRequestx_GSax_ + 56
    ...
)

Answer 1

问题的直接原因是，当您使用indexPath时，您正在使用newIndexPath进行行更新。

原因是indexPath是之前任何插入或删除的索引，而newIndexPath是插入和删除之后的索引。

如果你想从fetchedResultsController更新tableView或collectionView并让它从不崩溃，你就是这样做的：有5个可变对象 - rowInsert，rowDelete，rowUpdate，sectionInsert，sectionDelete。 rowInsert，rowDelete和rowUpdate是indexPaths的可变数组（即NSMutableArray<NSIndexPath*>*）。 sectionInsert和sectionDelete是可变索引集（即NSMutableIndexSet*）。在controllerWillChangeContent中清除数组。在每次更改时添加适当的indexPath。对于插入和更新，请使用newIndexPath，对于删除使用indexPath，将add newIndexPath移至rowInsert，将indexPath移至rowDelete。在controllerDidChangeContent排序rowInsert和sectionInsert升序和排序sectionDelete和rowDelete降序。（您可以按行它的顺序保留rowUpdate。）现在按以下顺序应用更改：rowDelete，sectionDelete，sectionInsert，rowInsert，rowUpdate。

谁在致电删除？

1 个答案: