# invalidateItems(at:) Marks the specified items as invalid so that their layout information can be updated. ``` func invalidateItems(at indexPaths: Set) ``` ## Parameters `indexPaths` A set of objects. Each index path represents an item whose layout needs to be recomputed. ## Discussion Call this method when you want the layout object to recompute attributes for a specific set of items. The items you provide are added to the [`invalidatedItemIndexPaths`](/documentation/AppKit/NSCollectionViewLayoutInvalidationContext/invalidatedItemIndexPaths) property. You can call this method more than once to create a merged set of items. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)