# subscribe(to:_:) Subscribes to an action event. ``` @MainActor @preconcurrency static func subscribe(to eventType: ActionEventType, _ handler: @escaping @MainActor (ActionEvent) -> Void) ``` ## Discussion For example, you can call this method to subscribe to the update event, which the system calls each frame it evaluates the action: ```swift struct MyAction: EntityAction { ... } MyAction.subscribe(to: .updated) { event in // RealityKit calls this closure in lock step as it // processes each animation frame. } ``` --- 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)