# register(action:) Register a custom action of given type. Each type of custom action needs to be registered before it can be used. ``` mutating func register(action type: Action.Type) where Action : BitwiseCopyable, Action : CustomAction ``` ## Parameters `type` The type of the custom action. --- 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)