# next() Produces the next element in the compact map sequence. ``` mutating func next() async throws -> ElementOfResult? ``` ## Discussion This iterator calls `next()` on its base iterator; if this call returns `nil`, `next()` returns `nil`. Otherwise, `next()` calls the transforming closure on the received element, returning it if the transform returns a non-`nil` value. If the transform returns `nil`, this method continues to wait for further elements until it gets one that transforms to a non-`nil` value. If calling the closure throws an error, the sequence ends and `next()` rethrows the error. --- 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)