# isolation() Produce a reference to the actor to which the enclosing code is isolated, or `nil` if the code is nonisolated. ``` @freestanding(expression) macro isolation() -> T ``` ## Overview If the type annotation provided for `#isolation` is not `(any Actor)?`, the type must match the enclosing actor type. If no type annotation is provided, the type defaults to `(any Actor)?`. --- 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)