👀 Views: 1 💬 Answers: 1 📅 Created: 2025-06-09

ios uicollectionview custom-layout Swift

I've spent hours debugging this and I'm experiencing unexpected behavior when implementing a custom layout for a `UICollectionView` in iOS 16. My custom layout class inherits from `UICollectionViewLayout`, and I'm trying to override the `layoutAttributesForElements(in:)` method to provide custom layout attributes. However, when I scroll through the collection view, the cells appear to overlap and sometimes disappear altogether. Here's a snippet of my layout class: ```swift class CustomLayout: UICollectionViewLayout { private var cache: [UICollectionViewLayoutAttributes] = [] private var contentHeight: CGFloat = 0 override func prepare() { guard cache.isEmpty else { return } let itemCount = collectionView?.numberOfItems(inSection: 0) ?? 0 let width = collectionView?.bounds.width ?? 0 for item in 0..<itemCount { let indexPath = IndexPath(item: item, section: 0) let attributes = UICollectionViewLayoutAttributes(forCellWith: indexPath) let height: CGFloat = 100 // Fixed height for simplicity attributes.frame = CGRect(x: 0, y: contentHeight, width: width, height: height) cache.append(attributes) contentHeight += height } } override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? { return cache.filter { $0.frame.intersects(rect) } } override func collectionViewContentSize() -> CGSize { return CGSize(width: collectionView?.bounds.width ?? 0, height: contentHeight) } } ``` The issue seems to arise when the collection view is set to use paging or has a custom flow layout. I've tried calling `invalidateLayout()` before the layout is prepared and adjusting the frame calculations, but the overlapping and disappearing cells persist. I also verified that the delegate and data source are correctly set up. I've checked the documentation and various forums for similar issues, but nothing seems to address this specific combination of custom layout with paging. Has anyone experienced this or can provide insights into what might be causing the cells to overlap or disappear? Any suggestions would be greatly appreciated! For context: I'm using Swift on macOS.