# withElements(_:) Provides read-only access to the per-vertex data within a callback. ``` func withElements(_ callback: (Span) -> Result) -> Result ``` ## Parameters `callback` A closure that receives a span over the per-vertex data. ## Return Value The value returned by `callback`. ## Discussion The provided span is only valid for the lifetime of the callback. --- 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)