iOS UICollectionView 崩溃 - NSInternalInconsistencyException 原因检测到无效的批量更新

Question

我试图在网络调用后更新集合视图，以将更多元素插入集合视图中。只有一节（第 0 节）。崩溃很难重现，我无法确切说明为什么会发生这种情况。该代码也是按照 Raywenderlich 的 answer 中建议的方式以及此 stackoverflow answer

建议的方式编写的

这是我的代码：

func process(_ difference: [CollectionDifference<User>.Change]?) {
        guard let difference = difference, !difference.isEmpty else {
            updateDataSource()
            collectionView.reloadData()
            return
        }
        let deleting = difference.contains { change in
            if case let .remove(offset: _, element: _, associatedWith: associatedWith) = change {
                return associatedWith == nil
            }
            return false
        }

        let inserting = difference.contains { change in
            if case let .insert(offset: _, element: _, associatedWith: associatedWith) = change {
                return associatedWith == nil
            }
            return false
        }

        isCollectionViewUpdating = true
        collectionView.performBatchUpdates({
            updateDataSource()
            for change in difference {
                switch change {
                case let .insert(offset: offset, element: recommendation, associatedWith: _):
                    collectionView.insertItems(at: [IndexPath(row: offset, section: 0)])
                case let .remove(offset: offset, element: _, associatedWith: _):
                    collectionView.deleteItems(at: [IndexPath(row: offset, section: 0)])
                }
            }
        }, completion: { [weak self] _ in
            guard let self = self else { return }
            self.isCollectionViewUpdating = false

            self.finalizingIndexPaths.removeAll()
            if deleting {
                self.paginate()
            } else if inserting {
                self.delegate?.didInsertInCollectionView()
            }
        })
    }

这是我遇到的错误消息

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid batch updates detected: the number of sections and/or items returned by the data source before and/or after performing the batch updates are inconsistent with the updates.
Data source before updates = { 1 section with item counts: [16] }
Data source after updates = { 1 section with item counts: [16] }
Updates = [
    Insert item (0 - 0),
    Insert item (0 - 1),
    Insert item (0 - 2),
    Insert item (0 - 3),
    Insert item (0 - 4),
    Insert item (0 - 5),
    Insert item (0 - 6),
    Insert item (0 - 7),
    Insert item (0 - 8),
    Insert item (0 - 9),
    Insert item (0 - 10),
    Insert item (0 - 11),
    Insert item (0 - 12),
    Insert item (0 - 13),
    Insert item (0 - 14),
    Insert item (0 - 15)
]

此外，包含 collectionView 的特定视图控制器将作为子视图控制器添加到其父视图控制器中。父视图控制器是选项卡栏控制器的一部分。

有处理 uicollectionview 的回调

public func willBecomeActive() {
   view.layoutIfNeeded()
   collectionView.reloadData()
   // need to add this empty performBatchUpdates, otherwise the cells don't
   // come on screen in tests
   collectionView.performBatchUpdates({}, completion: nil)
}

public func didResignActive() {
    collectionView.reloadData()
}

override public func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    collectionViewFlowLayout.updateItemSize()

    // helps to correctly resizes the cells.
    UIView.performWithoutAnimation {
       collectionView.performBatchUpdates({}, completion: nil)
    }
}

有人可以发现我的代码的问题并提供帮助吗？

我尝试用新用户加载collectionview并替换旧用户。我期待新用户成功插入。但有时我会遇到难以解释的崩溃。崩溃的错误消息如上

Answer 1

不知道您是否已经解决了这个问题，但在我看来，您收到的错误告诉您您正在尝试插入或删除项目，即使您的集合视图的源没有改变。如果没有看到更多，很难判断这是否真的是问题所在