Question

我正在使用NSFetchedResultsController和UICollectionView创建媒体库。由于使用NSFetchedResultsControllerDelegate在collectionView上应用更新存在很多问题，因此我正在使用以下实现：

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

    if type == .insert {
        blockOperations.append(
            BlockOperation(block: { [weak self] in
                self?.collectionView.insertSections(IndexSet(integer: sectionIndex))
            })
        )
    } else if type == .update {
        blockOperations.append(
            BlockOperation(block: { [weak self] in
                self?.collectionView.reloadSections(NSIndexSet(index: sectionIndex) as IndexSet)
            })
        )
    } else if type == .delete {
        blockOperations.append(
            BlockOperation(block: { [weak self] in
                self?.collectionView.deleteSections(NSIndexSet(index: sectionIndex) as IndexSet)
            })
        )
    }
}

func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {

    if type == .insert {
        if self.collectionView.numberOfSections > 0 {

            guard let newIndexPathSection = newIndexPath?.section else {
                return
            }

            if self.collectionView.numberOfItems(inSection: newIndexPathSection) == 0 {
                self.shouldReloadCollectionView = true
            } else {

                guard let newIndexPath = newIndexPath else {
                    return
                }

                self.blockOperations.append(
                    BlockOperation(block: { [weak self] in
                        self?.collectionView.insertItems(at: [newIndexPath])
                    })
                )
            }

        } else {
            self.shouldReloadCollectionView = true
        }


    } else if type == .update {
        guard let indexPath = indexPath else {
            return
        }
        self.blockOperations.append(
            BlockOperation(block: { [weak self] in
                self?.collectionView.reloadItems(at: [indexPath])
            })
        )
    } else if type == .move {
        guard let indexPath = indexPath, let newIndexPath = newIndexPath else {
            return
        }
        self.blockOperations.append(
            BlockOperation(block: { [weak self] in
                self?.collectionView.moveItem(at: indexPath, to: newIndexPath)
            })
        )
    } else if type == .delete {

        guard let indexPath = indexPath else {
            return
        }

        if self.collectionView.numberOfItems(inSection: indexPath.section) == 1 {
            self.shouldReloadCollectionView = true
        } else {
            self.blockOperations.append(
                BlockOperation(block: { [weak self] in
                    self?.collectionView.deleteItems(at: [indexPath])
                })
            )
        }
    }
}



func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
    if shouldReloadCollectionView {
        self.collectionView.reloadData()
    } else {
        self.collectionView.performBatchUpdates({
            for operation: BlockOperation in self.blockOperations {
                operation.start()
            }
        }, completion: { _ in
            self.blockOperations.removeAll(keepingCapacity: false)
        })
    }
}

当保存大量媒体时，很显然索引有很多更改。因此会引发错误：

***由于未捕获的异常“ NSInternalInconsistencyException”而终止应用程序，原因：“请求的数量集合中只有1个部分时，第1部分中的项目查看”

我发现这是在致电时发生的：

collectionView.numberOfItems(inSection: newIndexPathSection)

调用controllerDidChangeAnObject时。

如何解决此错误？谢谢

CollectionView：当集合视图中只有1个部分时，请求第1部分中的项目数

0 个答案: