# transform(updating:body:) Tracks the location of the provided range throughout the mutation closure, returning a new, updated range that represents the same effective locations after the mutation. ``` mutating func transform(updating range: Range, body: (inout AttributedString) throws(E) -> Void) throws(E) -> Range? where E : Error ``` ## Parameters `range` A range to track throughout the `body` block. `body` A mutating operation, or set of operations, to perform on this `AttributedString`. ## Return Value the updated `Range` that is valid after the mutation has been performed, or `nil` if the mutation performed does not allow for tracking to succeed (such as replacing the provided inout variable with an entirely different `AttributedString`). --- 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)