# BehaviorTreeAction A protocol that defines an action that a behavior tree action node can use. ``` protocol BehaviorTreeAction : EntityAction ``` ## Overview Conform to this protocol as: ```swift struct CustomBehaviorTreeAction: BehaviorTreeAction, Codable { public var isReversible: Bool { false } public var isAdditive: Bool { false } public var animatedValueType: (any AnimatableData.Type)? { nil } // Add your action-specific properties, functions and subscriptions here. } ``` ## Topics ### Subscribing to events [`static func subscribe(to: ActionEventType, (ActionEvent) -> ActionResult)`](/documentation/RealityKit/BehaviorTreeAction/subscribe(to:_:)-9mrvx) Subscribes to a serializable action event and returns a `ActionResult`. [`static func subscribe(to: ActionEventType, (ActionEvent) -> Void)`](/documentation/RealityKit/BehaviorTreeAction/subscribe(to:_:)-3p0pj) Shadows the `EntityAction.subscribe(to:_:)` overload that takes a `-> Void` closure. ### Type Methods [`static subscribe(to:_:)`](/documentation/RealityKit/BehaviorTreeAction/subscribe(to:_:)) Subscribes to a serializable action event and returns a `ActionResult`. ## Relationships ### Inherits From [`EntityAction`](/documentation/RealityKit/EntityAction) --- 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)