# BehaviorTreeResource An immutable representation of a behavior tree. ``` class BehaviorTreeResource ``` ## Overview A `BehaviorTreeResource` can be produced by compiling a tree definition. Once compiled, assign it to an entity via [`BehaviorTreeComponent`](/documentation/RealityKit/BehaviorTreeComponent) to begin driving behaviors: let treeResource1 = try BehaviorTreeResource(definition: Data(behaviorTreeDefinition1.utf8)) let treeResource2 = try BehaviorTreeResource(definition: Data(behaviorTreeDefinition2.utf8)) let treeResources: [String : BehaviorTreeResource] = [“tree1” : treeResource1, “tree2” : treeResource2] entity.components.set(BehaviorTreeComponent(behaviorTree: resource, availableBehaviorTrees: treeResources)) ## Parameters The tree exposes a set of named parameters that control its behavior at runtime, such as movement speed. Read the available parameters via [`parameterNames`](/documentation/RealityKit/BehaviorTreeResource/parameterNames). To set values at runtime, use the entity’s parameter binding: entity.parameters[“MoveSpeed”] = BindableValue(Float(1.0)) ## Topics ### Creating a behavior tree [`convenience init(definition: Data) throws`](/documentation/RealityKit/BehaviorTreeResource/init(definition:)) Compile a new resource from data, throws on failure. ### Validating a definition [`static func validate(definition: Data) -> [String]`](/documentation/RealityKit/BehaviorTreeResource/validate(definition:)) Run the compiler and return all tree errors without producing a resource. ### Accessing parameters [`var parameterNames: [String]`](/documentation/RealityKit/BehaviorTreeResource/parameterNames) Returns the names of all parameters in the behavior tree resource. ## Relationships ### Conforms To [`Resource`](/documentation/RealityKit/Resource) [`Sendable`](/documentation/Swift/Sendable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) --- 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)