RealityKit API Reference

API reference for RealityKit, organized by category: the Entity hierarchy, built-in components, the System protocol, the SwiftUI views (RealityView, Model3D), materials, physics, animation, audio, Metal integration, and the 27-release additions.

When to Use This Reference

Use this reference when:

• Looking up specific RealityKit API signatures or properties
• Checking which component types are available
• Finding the right anchor type for an AR experience
• Browsing material properties and options
• Setting up physics body parameters
• Looking up animation or audio API details
• Checking platform availability for specific APIs
• Browsing the 27-release additions (navigation mesh, level of detail, soft shadows, Gaussian splats, reverb, cloth, ComputeGraph, the low-level renderer)

Example Prompts

Questions you can ask your assistant that will draw from this reference:

• "What properties does PhysicallyBasedMaterial have?"
• "How do I create a RealityView with attachments?"
• "What are the ShapeResource types for collision?"
• "What events can I subscribe to in RealityKit?"
• "How do I set up spatial audio on an entity?"
• "What Entity subclasses are available?"
• "How do I render RealityKit content from my own Metal command buffer?"
• "Can I build a shader graph in Swift instead of Reality Composer Pro?"
• "How do I generate an image-based light at runtime from an HDR?"
• "Why won't import RealityCoreRenderer compile?"

What's Covered

• Entity API – Creation, properties (isEnabled, isAnchored, scene), hierarchy methods, and nine Entity subclasses (ModelEntity, AnchorEntity, PerspectiveCamera, lights, TriggerVolume, ViewAttachmentEntity, BodyTrackedEntity)
• Component catalog – Built-in components including Transform, ModelComponent, CollisionComponent, PhysicsBodyComponent, PhysicsMotionComponent, CharacterControllerComponent, AnchoringComponent, light components, AccessibilityComponent, and InputTargetComponent; shape resources and plane classification
• MeshResource generators – Box, sphere, plane, cylinder, cone, text
• System protocol – SceneUpdateContext, EntityQuery (has/and/not), and eight event types (scene, collision, and animation events)
• RealityView API – Initializers (basic, update, placeholder, attachments), RealityViewContent, gesture integration (tap, drag, rotate, magnify)
• Model3D API – Simple display, phase handling, URL loading
• Material system – SimpleMaterial, PhysicallyBasedMaterial (full PBR), UnlitMaterial, OcclusionMaterial, VideoMaterial, TextureResource loading
• Animation – Transform animation with timing functions, USD animation playback, AnimationPlaybackController
• Audio – AudioFileResource, SpatialAudioComponent, AmbientAudioComponent, ChannelAudioComponent, playback control
• RealityRenderer – Rendering a RealityKit scene into Metal textures
• RealityKit 27 additions – Navigation mesh pathfinding, level of detail, soft shadows, projective textures, physical space lighting (visionOS and macOS), lightmaps, Gaussian splats, custom reverb meshes, ARKit object tracking (iOS), cloth simulation (ClothBodyComponent; iOS, macOS, and visionOS), and the ComputeGraph framework for building compute node graphs in code
• More 27 components – Bloom, tone mapping, clipping, PBR decals, occlusion culling, render layers, lighting models (including hair), subsurface scattering, mesh deformers, skeletal retargeting and IK, animation graphs, behavior trees, diffuse light probes, USDStageComponent

Renderer Submodules (27 Releases)

The low-level renderer drives RealityKit's shading from your own MTLCommandBuffer, with no entities. It and the ShaderGraph, deformation, and texture-processing submodules are reached through import RealityKit; none of them can be imported directly.

• Frame loop – LowLevelRenderer (output, cameras, time, colorMatch, render(using:_:)), Configuration, Camera / CameraArray, RenderState
• Resource context – LowLevelRenderContext, …Standalone, …Lighting, …ShaderGraph
• Resources – LowLevelMeshResource, LowLevelTextureResource, LowLevelBufferResource, LowLevelInstanceTransformResource
• Materials and pipeline – LowLevelMaterialResource, LowLevelArgumentTable, LowLevelRenderPipelineState, LowLevelRenderTarget.Descriptor
• Draw, cull, sort – LowLevelMeshPart, LowLevelMeshInstance, LowLevelMeshInstanceArray, cullMeshInstances, sortMeshInstances
• Name-collision table – the 26-era LowLevelMesh / LowLevelTexture / LowLevelBuffer / LowLevelInstanceData versus their 27 *Resource counterparts
• ShaderGraph in Swift – ShaderGraph, NodeLibrary, NodeDefinition, Node, Edge, ShaderGraphMaterial.Program / Program.Descriptor
• GPU mesh deformation – LowLevelDeformationContext, LowLevelDeformation
• Runtime skybox and IBL – SkyboxGenerator, ImageBasedLightTextureGenerator, TextureSamplingQuality

Documentation Scope

This page documents the realitykit-ref skill (in the axiom-graphics suite). Rendering a USDKit stage with USDStageComponent is covered in depth in USDKit.

Related

• RealityKit – Entity-component-system (ECS) architecture patterns and best practices
• RealityKit Diagnostics – Troubleshooting invisible entities, physics, and rendering
• SceneKit API Reference – SceneKit equivalents for migration reference
• SpriteKit API Reference – 2D game framework (complements RealityKit's 3D)

Resources

WWDC: 2019-603, 2019-605, 2021-10074, 2022-10074, 2023-10080, 2024-10103, 2024-10153, 2026-279

Docs: /realitykit, /realitykit/entity, /realitykit/component, /realitykit/system, /realitykit/realityview, /realitykit/model3d, /realitykit/modelentity, /realitykit/anchorentity, /realitykit/physicallybasedmaterial, /computegraph