# ForceEffectEvent A struct that defines the arguments to the custom force effect update closure. ``` struct ForceEffectEvent where ForceEffectType : ForceEffectProtocol ``` ## Overview If you register your custom force effect using a closure, you can access the force effect’s property and [`ForceEffectParameters`](/documentation/RealityKit/ForceEffectParameters) from this struct. ## Topics ### Instance Properties [`var effect: ForceEffectType`](/documentation/RealityKit/ForceEffectEvent/effect) The force effect to update. [`var parameters: ForceEffectParameters`](/documentation/RealityKit/ForceEffectEvent/parameters) Physics body parameters. --- 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)