[UICollectionView setCollectionViewLayout上的错误访问：动画：] [英] Bad Access on [UICollectionView setCollectionViewLayout:animated:]

问题描述

我在UICollectionView中遇到了一个奇怪的崩溃。
崩溃的UICollectionView嵌入在另一个UICollectionView的UICollectionView单元格中。

I'm getting a strange crash in my UICollectionView. The crashing UICollectionView is embedded in an UICollectionView cell of another UICollectionView.

我无法重现这个问题，有时如果内部UICollectionView得到的话似乎会发生新初始化，因为外部CollectionView正在重新加载它的单元格。

I can't reproduce the issue, it seems to happen sometimes if the inner UICollectionView get's newly initialized because the outer CollectionView is reloading it's cells.

com.apple.main-thread Crashed
0   libobjc.A.dylib     objc_msgSend + 9
1   UIKit   -[UICollectionViewData _setLayoutAttributes:atGlobalItemIndex:] + 60
2   UIKit   __45-[UICollectionViewData validateLayoutInRect:]_block_invoke_0 + 668
3   UIKit   -[UICollectionViewData validateLayoutInRect:] + 1408
4   UIKit   -[UICollectionViewData layoutAttributesForElementsInRect:] + 82
5   UIKit   -[UICollectionView setCollectionViewLayout:animated:] + 1644
6   MyApp   BSCTopnewsCollectionView.m line 52 -[BSCTopnewsCollectionView setupBSCTopnewsCollectionView]
7   MyApp   BSCTopnewsCollectionView.m line 27 -[BSCTopnewsCollectionView setWeakDelegatePointer:]
8   Myapp   BSCFrontPageViewController.m line 550 -[BSCFrontPageViewController collectionView:cellForItemAtIndexPath:]
9   UIKit   -[UICollectionView _createPreparedCellForItemAtIndexPath:withLayoutAttributes:] + 252
10  UIKit   -[UICollectionView _updateVisibleCellsNow:] + 2672
11  UIKit   -[UICollectionView layoutSubviews] + 214
12  UIKit   -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 258
13  QuartzCore  -[CALayer layoutSublayers] + 214
14  QuartzCore  CA::Layer::layout_if_needed(CA::Transaction*) + 460
15  QuartzCore  CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 16
16  QuartzCore  CA::Context::commit_transaction(CA::Transaction*) + 238
17  QuartzCore  CA::Transaction::commit() + 316
18  QuartzCore  CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 60
19  CoreFoundation  __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 20
25  UIKit   UIApplicationMain + 1120
26  MyApp   main.m line 16 main 


Exception Type:
    EXC_BAD_ACCESS
Code:
    KERN_INVALID_ADDRESS at 0x158848 

我在setupBSCTopnewsCollectionView的第52行所做的是

What I'm doing in line 52 in setupBSCTopnewsCollectionView is

BSCInfiniteLayout *infiniteLayout = [[BSCInfiniteLayout alloc] init];    

(line 52) self.collectionView.collectionViewLayout = infiniteLayout;

---

---

编辑： - [BSCFrontPageViewController collectionView：cellForItemAtIndexPath：]

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    if([collectionView isEqual:self.collectionView])
    {
        if(indexPath.row == 0) // Header Cell
        {
            BSCTopnewsCollectionView *cell = [collectionView dequeueReusableCellWithReuseIdentifier:BSCHeaderReuseIdentifier forIndexPath:indexPath];
            cell.dataSource = self;
            cell.weakDelegatePointer = self;

            self.topNewsCollectionView = cell;

            return cell;
        }
        else
        {
            //create normal cells
        }
    }
    else if ([collectionView isEqual:self.topNewsCollectionView.collectionView])
    {
        BSCTopNewsHeaderCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:BSCTopNewsCellReuseIdentifier forIndexPath:indexPath];
        BSCNews *topnews = [self.topNews objectAtIndex:indexPath.row];

        [cell setEntity:topnews];

        return cell;
    }
}

方法调用的一些说明：

- (void)setWeakDelegatePointer:(BSCFrontPageViewController *)weakDelegatePointer
{
    _weakDelegatePointer = weakDelegatePointer;

    [self setupBSCTopnewsCollectionView];
    [self.collectionView reloadData];
}

- (void)setupBSCTopnewsCollectionView
{
    self.collectionView.delegate = self.weakDelegatePointer;
    self.collectionView.dataSource = self.weakDelegatePointer;

    BSCInfiniteLayout *infiniteLayout = [[BSCInfiniteLayout alloc] init];


    infiniteLayout.delegate = self;

    // Setup Layout
    self.collectionView.collectionViewLayout = infiniteLayout;
    self.collectionView.showsHorizontalScrollIndicator = NO;
    self.collectionView.pagingEnabled = YES;

    // Register Cells
    [self.collectionView registerNib:[UINib nibWithNibName:@"BSCTopNewsHeaderCell" bundle:nil] forCellWithReuseIdentifier:BSCTopNewsCellReuseIdentifier];
}

---

---

Edit3 ：崩溃似乎只发生在特殊场合。
如果应用程序在后台，但仍在内存中，用户再次打开它。然后它会检查我们的API以获取新数据，如果发现某些内容会加载它们并重新加载整个外部集合视图。这是崩溃发生的时候。

---

---

Edit3: The crash only seems to occur in special occasions. If the app was in the background, but still in memory and the user opens it up again. It then checks our API for new data, and if it found something will load them and reload the whole outer collectionView. Thats when the crash occurs.

如果在应用程序运行时重新加载CollectionView而不是在开始时在后台，一切都很好。

If the CollectionView is reloaded while the app is running without being in the background in the beginning everything is fine.

---

使设置更清晰一点。

---

To make the setup a bit more clear.

推荐答案

从评论中删除我们的答案。

Pulling our "Answer" out of the comments.

可悲的是，没有一个答案有帮助。我最终重构了整个事情然后问题消失了。我甚至与苹果DTS工程师进行了非常详细的交谈，他也不知道该怎么做。所以我们只是重构了。对不起：/

Sadly none of the answers helped. I ended up refactoring the whole thing and then the problem disappeared. I even had an pretty detailed talk with an apple DTS engineer who also didn't knew what to do. So we just refactored. Sorry :/

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