# next() Produces the next element in the flat map sequence. ``` mutating func next() async throws -> SegmentOfResult.Element? ``` ## 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, takes the resulting asynchronous sequence, and creates an asynchronous iterator from it. `next()` then consumes values from this iterator until it terminates. At this point, `next()` is ready to receive the next value from the base sequence. If `transform` throws an error, the sequence terminates. --- 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)