Crash in iOS18

Question

Created Jun ’24

Replies 27

Boosts 19

Views 27k

Participants 50

I have a UITableView which contains a UICollectionView in the first row. It used to work fine in iOS17, but now I get a crash when running with Xcode 16 / iOS18 beta:

Expected dequeued view to be returned to the collection view in preparation for display. When the collection view's data source is asked to provide a view for a given index path, ensure that a single view is dequeued and returned to the collection view. Avoid dequeuing views without a request from the collection view. For retrieving an existing view in the collection view, use -[UICollectionView cellForItemAtIndexPath:] or -[UICollectionView supplementaryViewForElementKind:atIndexPath:]

This is my UITableView delegate call:

    AddEditDataCell *cell = nil;
    if (indexPath.section == 0) {
        
        if (indexPath.row == 0) {
            AddEditDataContactsCell *contactNameCell = (AddEditDataContactsCell *)[self cellForContactNamesCollectionAtIndexPath:indexPath tableView:tableView];
            return contactNameCell; 


- (AddEditDataContactsCell *)cellForContactNamesCollectionAtIndexPath:(NSIndexPath *)indexPath tableView:(UITableView *)tableView {
    AddEditDataContactsCell *contactsCell = (AddEditDataContactsCell *)[self.tableView dequeueReusableCellWithIdentifier:@"ContactsCell" forIndexPath:indexPath];
    if (self.collectionNameCell == nil) {
        self.collectionNameCell = [contactsCell.collectionView dequeueReusableCellWithReuseIdentifier:@"LogContactNameCollectionCellIdentifier" forIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]];
        contactsCell.nameCellDelegate = self;
    }

    contactsCell.frame = CGRectZero;
    [contactsCell setNeedsLayout];
    [contactsCell.collectionView reloadData];
    
    contactsCell.collectionViewHeightConstraint.constant = contactsCell.collectionView.collectionViewLayout.collectionViewContentSize.height;
    
    [contactsCell.collectionView.collectionViewLayout invalidateLayout];
    return contactsCell;
}

Answer 1

lockSee OP

Dec ’24

I want to share that I had exactly the same crash description, but my issue was related to NSFetchedResultsControllerDelegate. After refactoring, issue disappeared. I hope it may help some of us who trying to find the root case.

Best way to debug is to enable Exception Breakpoint.

Crash was called in this function inside the batch update. Worked fine on Xcode 15, but crashes on Xcode 16.

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
        collectionView?.performBatchUpdates({

          //crash was here

        }, completion: { [weak self] finished in
            //completion
        })
    }
}

Answer 2

KarishmaGR OP

Feb ’25

Hi all,

I’ve resolved the issue by updating my collectionView settings. This crash was occurring only on iOS 18, and the following line fixed it for me:

collectionView.isPrefetchingEnabled = false

Disabling prefetching prevented the crash and everything is working smoothly now