RealityKit

RealityKit
Information
Type	3D Framework / Software Development Kit
Industry	Augmented Reality / Virtual Reality
Developer	Apple Inc.
Written In	Swift
Operating System	iOS 13.0+, iPadOS 13.0+, macOS 10.15+, visionOS 1.0+, tvOS 18.0+
License	Proprietary
Supported Devices	iPhone, iPad, Mac, Apple Vision Pro, Apple TV 4K
Release Date	June 3, 2019
Website	https://developer.apple.com/realitykit/

RealityKit is a high-performance 3D framework developed by Apple Inc. for creating augmented reality (AR) and spatial computing experiences across Apple platforms. The RealityKit framework was built from the ground up specifically for augmented reality with photo-realistic rendering, camera effects, animations, physics, and more. RealityKit was first introduced along with iOS 13, iPadOS 13, and macOS 10.15 (Catalina) on June 3 at the 2019 Worldwide Developers Conference. The framework provides developers with native Swift APIs for realistic rendering, animation, physics simulation, and spatial audio, making AR development more accessible and efficient.

Overview

RealityKit serves as Apple's primary 3D rendering and simulation engine for AR applications, designed to work seamlessly with ARKit to create immersive experiences. RealityKit provides high-performance 3D simulation and rendering capabilities you can use to create visionOS apps or to create augmented reality (AR) apps for iOS, macOS, and tvOS. The framework emphasizes ease of use while providing powerful capabilities for professional-grade AR experiences.

RealityKit is an AR first framework, which means that it's been completely designed from the ground up with an emphasis on AR application development. It leverages the power of Metal for optimized performance on Apple devices and integrates deeply with other Apple frameworks to provide a comprehensive AR development platform.

History

Initial Release (2019)

RealityKit was first introduced along with iOS 13, iPadOS 13, and macOS 10.15 (Catalina) on June 3 at the 2019 Worldwide Developers Conference. The framework was announced alongside Reality Composer, a companion tool for creating AR content without coding.

RealityKit 2 (2021)

RealityKit 2 was introduced with iOS 15, iPadOS 15, and macOS 12 (Monterey) on June 8 at the 2021 Worldwide Developers Conference. It adds support for Object Capture and other APIs. RealityKit 2 introduces a bunch of new features to help you make even more immersive AR apps and games, including custom shaders and materials, custom systems, and character controllers.

RealityKit 4 (2024)

RealityKit 4 was introduced with the first public betas of iOS 18, iPadOS 18, and macOS 15 (Sequoia) on July 15, 2024. With RealityKit 4, you can build for iOS, iPadOS, macOS, and visionOS — all at once. This version aligned features across all Apple platforms and introduced support for visionOS.

tvOS Support (2025)

This year I'm proud to announce that RealityKit is now supported on the latest tvOS! Now you can bring your existing apps and experiences to AppleTV or create new ones for the big screen.

Architecture

Entity Component System

RealityKit uses an Entity Component System (ECS) architecture for organizing and managing 3D content. ECS, short for entity component system, is a way of structuring data and behavior, and it's commonly used in games and simulations.

Core ECS Elements

Element	Description	Purpose
Entity	An entity is a container object	Represents objects in the scene
Component	Each component enables some specific behavior for an entity	Defines properties and behaviors
System	Systems are a really effective way to implement a variety of effects and behaviors	Processes entities with specific components

Key Components

RealityKit provides numerous built-in components for common AR functionality:

• ModelComponent: Provides mesh and materials for rendering
• Transform: Positions entities in 3D space
• CollisionComponent: Enables physics interactions
• AnchoringComponent: Anchors content to real-world features
• AudioComponent: Adds spatial audio
• AnimationComponent: Enables animations
• HoverEffectComponent: Provides visual feedback on gaze (visionOS)

Features

Rendering

RealityKit seamlessly blends virtual content with the real world using realistic, physically based materials, environment reflections, grounding shadows, camera noise, motion blur, and more to make virtual content nearly indistinguishable from reality. The rendering system includes:

• Physically Based Rendering (PBR)
• Real-time shadows and reflections
• Post-processing effects
• Custom materials and shaders
• Video textures
• HDR support

Physics Simulation

With a powerful physics engine, RealityKit lets you throw anything at it — pun intended! You can adjust real-world physics properties like mass, drag and restitution, allowing you to fine-tune collisions. Features include:

• Rigid body dynamics
• Collision detection
• Real-world occlusion
• Scene understanding integration

Animation

RealityKit supports multiple animation types:

• Transform-based animations
• Skeletal animations
• Blend shapes
• Custom animation timelines
• Procedural animations through custom systems

Spatial Audio

Spacial audio understanding and automatic listener configuration let you attach sound effects to 3D objects. You can then track those sounds, making them sound realistic based on their position in the real world.

Cross-Platform Support

Platform Availability

Platform	Minimum Version	Notes
iOS	13.0+	Full feature set
iPadOS	13.0+	LiDAR support on compatible devices
macOS	10.15+	Object Capture API available
visionOS	1.0+	Additional immersive features
tvOS	18.0+	Added in 2025

Integration with Other Technologies

ARKit Integration

ARKit integrates hardware sensing features to produce augmented reality apps and games combining device motion tracking, world tracking, scene understanding, and display conveniences to simplify building an AR experience. RealityKit uses ARKit for:

• Device tracking and localization
• Plane detection
• Object detection
• Face tracking
• Body tracking
• Scene understanding with LiDAR

Reality Composer Pro

Reality Composer Pro, a new tool that launched with Apple Vision Pro, enables development of spatial apps on all these platforms. This tool allows developers to:

• Create and edit 3D scenes visually
• Design particle effects
• Configure physics properties
• Set up animations
• Build shader graphs with MaterialX

SwiftUI Integration

RealityKit provides several ways to integrate with SwiftUI:

• Model3D: Simple view for displaying 3D models
• RealityView: Full-featured view for complex scenes
• Attachment system for embedding SwiftUI views in 3D space

Development Tools

Required Tools

• Xcode 11.0 or later
• macOS 10.15 or later for development
• Swift 5.0 or later

File Formats

• USDZ: Primary 3D asset format
• USD: Universal Scene Description
• Reality files from Reality Composer

Notable Features by Version

RealityKit 2 Features

• Object Capture API
• Custom render pipelines
• Character controllers
• Geometry modifiers
• Custom systems

RealityKit 4 Features

• Cross-platform alignment
• Portal effects
• Blend shapes
• Inverse kinematics
• Direct ARKit data access
• Hover effects (visionOS)

Advanced Features

Object Capture

The Object Capture API, introduced in RealityKit 2, uses photogrammetry to turn a series of pictures taken on iPhone or iPad into 3D models that can be viewed instantly in AR Quick Look. This feature enables:

• Creation of 3D models from photos
• Automatic texture generation
• Optimized mesh generation
• Export to USDZ format

Scene Understanding

By combining information from the LiDAR Scanner and edge detection in RealityKit, virtual objects are able to interact with your physical surroundings. Features include:

• Automatic occlusion handling
• Real-world physics interactions
• Mesh classification (walls, floors, ceilings)
• Semantic understanding of spaces

Portals

Portal features in RealityKit 4 enable:

• Creation of windows into virtual spaces
• Smooth portal crossing animations
• Multiple portal configurations
• Custom portal shaders

Custom Rendering

RealityKit gives you more control over the rendering pipeline with:

• Custom render targets
• Metal compute shader integration
• Post-processing effects
• Custom material shaders
• Render pipeline customization

Platform-Specific Features

iOS and iPadOS

• Full ARKit integration
• Touch-based interactions
• LiDAR support on Pro models
• People occlusion
• Motion capture

macOS

• Non-AR 3D rendering
• Mouse and keyboard input
• Higher performance capabilities
• Development tools integration

visionOS

• Hand tracking integration
• Eye tracking support (privacy-preserving)
• Immersive spaces
• RealityView attachments
• Hover effects
• Spatial audio enhancements

tvOS

• Remote control input
• Living room scale experiences
• Simplified physics
• Optimized for TV displays

Asset Pipeline

Supported Formats

Asset Format Support

Format	Type	Notes
USDZ	3D Models	Apple's preferred format
USD	3D Scenes	Universal Scene Description
Reality	Composed Scenes	From Reality Composer
JPEG/PNG	Textures	Standard image formats
HEIF	Textures	High-efficiency format
MP4/MOV	Video Textures	For VideoMaterial

Asset Creation Workflow

1. Model creation in 3D software
2. Export to supported format
3. Optimization in Reality Composer Pro
4. Integration into Xcode project
5. Runtime loading in RealityKit

Debugging and Profiling

Xcode Integration

Xcode view debugging now supports inspecting 3D scene content, making it easier to:

• Inspect entity hierarchies
• View component properties
• Debug transform issues
• Analyze performance metrics

Performance Tools

• Instruments profiling
• GPU Frame Capture
• Metal System Trace
• Memory debugging

Performance

Utilizing the latest Metal features to get the most out of the GPU, RealityKit takes full advantage of CPU caches and multiple cores to deliver incredibly fluid visuals and physics simulations. The framework automatically scales performance based on device capabilities.

Use Cases

RealityKit is commonly used for:

• AR gaming experiences
• Product visualization
• Educational applications
• Architectural visualization
• Social AR experiences
• Industrial training
• Medical visualization

Code Examples

Basic Scene Setup

A simple example of creating a RealityKit scene in Swift:

import RealityKit
import ARKit

// Create AR view
let arView = ARView(frame: .zero)

// Create anchor
let anchor = AnchorEntity(plane: .horizontal)

// Create entity with model
let box = ModelEntity(mesh: .generateBox(size: 0.1))
box.model?.materials = [SimpleMaterial(color: .blue, isMetallic: true)]

// Add to scene
anchor.addChild(box)
arView.scene.anchors.append(anchor)

Entity Component Example

Example of creating a custom component:

struct RotationComponent: Component {
    var speed: Float = 1.0
}

class RotationSystem: System {
    required init(scene: Scene) { }
    
    func update(context: SceneUpdateContext) {
        for entity in context.entities(matching: EntityQuery(where: .has(RotationComponent.self))) {
            entity.transform.rotation *= simd_quatf(angle: context.deltaTime, axis: [0, 1, 0])
        }
    }
}

Technical Specifications

Supported Mesh Types

• Primitives: Box, Sphere, Cylinder, Cone, Torus, Plane
• Custom meshes via MeshResource
• Procedural mesh generation
• Low-level mesh APIs for direct manipulation

Material Types

Available Material Types

Material Type	Description	Use Case
SimpleMaterial	Basic material with color and metallic properties	Quick prototyping
UnlitMaterial	Material without lighting calculations	UI elements, effects
OcclusionMaterial	Hides virtual content behind real objects	AR occlusion
VideoMaterial	Displays video content on surfaces	Dynamic textures
PhysicallyBasedMaterial	Advanced PBR material	Realistic rendering
CustomMaterial	Shader-based custom materials	Special effects

Coordinate System

RealityKit uses a right-handed coordinate system where:

• X-axis points right (red)
• Y-axis points up (green)
• Z-axis points forward (blue)
• Units are in meters

Networking and Collaboration

RealityKit simplifies building shared AR experiences by taking on the hard work of networking, such as maintaining a consistent state, optimizing network traffic, handling packet loss, or performing ownership transfers. The framework includes:

• Automatic synchronization of entities
• MultipeerConnectivity integration
• Ownership transfer mechanisms
• Network optimization features

Best Practices

Performance Optimization

• Use Level of Detail (LOD) for complex models
• Implement frustum culling
• Optimize texture sizes
• Batch similar materials
• Use instancing for repeated objects

Memory Management

• Load assets asynchronously
• Unload unused resources
• Use texture compression
• Implement proper entity lifecycle management

Limitations

• Maximum texture size varies by device
• Physics simulation limits based on device capabilities
• Network synchronization limited to local networks
• Custom shaders require Metal Shading Language knowledge

Community and Resources

Official Resources

• Apple Developer Forums
• WWDC Sessions
• Sample Code Projects
• Technical Documentation

Third-Party Resources

• RealityKit-Sampler (GitHub)
• Awesome-RealityKit (GitHub)
• Various tutorials and courses

Future Development

Apple continues to expand RealityKit's capabilities with each release, focusing on:

• Enhanced cross-platform features
• Improved performance optimization
• Advanced rendering techniques
• Better integration with AI and machine learning
• Expanded spatial computing capabilities

Related Frameworks

• SceneKit: Older 3D graphics framework
• SpriteKit: 2D graphics framework
• GameplayKit: Game logic framework
• Core ML: Machine learning integration
• Vision: Computer vision framework

Industry Impact

RealityKit has significantly influenced the AR development landscape by:

• Lowering the barrier to entry for AR development
• Establishing standards for AR content creation
• Driving adoption of spatial computing
• Enabling new categories of AR applications

Awards and Recognition

While specific awards for RealityKit are not documented, the framework has been widely praised by developers for its ease of use and powerful capabilities, contributing to numerous award-winning AR applications on the App Store.

See Also

• ARKit
• Reality Composer
• Metal (API)
• visionOS
• Apple Vision Pro
• Swift (programming language)
• Augmented Reality
• Universal Scene Description
• MaterialX
• Spatial Computing

Accessibility

RealityKit includes several accessibility features:

• VoiceOver support for AR content
• Reduced motion options
• High contrast mode support
• Accessibility labels for 3D objects
• Alternative input methods

Security and Privacy

Privacy Features

• No direct camera access required
• Privacy-preserving eye tracking (visionOS)
• Secure asset loading
• Sandboxed execution environment

Security Considerations

• Code signing for custom shaders
• Secure network communications
• Protected asset formats
• Runtime security checks

Version Compatibility

RealityKit Version Compatibility

RealityKit Version	iOS/iPadOS	macOS	visionOS	tvOS	Key Features
1.0	13.0+	10.15+	-	-	Initial release
2.0	15.0+	12.0+	-	-	Object Capture, Custom Systems
3.0	16.0+	13.0+	-	-	Improved performance
4.0	17.0+	14.0+	1.0+	-	Cross-platform alignment
5.0	18.0+	15.0+	2.0+	18.0+	tvOS support

Comparison with Other Frameworks

AR/3D Framework Comparison

Feature	RealityKit	SceneKit	Unity	Unreal Engine
Language	Swift	Swift/Obj-C	C#	C++
Platform	Apple only	Apple only	Cross-platform	Cross-platform
AR Focus	Yes	Partial	Partial	Partial
Performance	Optimized	Good	Variable	High
Learning Curve	Moderate	Moderate	Steep	Very Steep
Asset Pipeline	Integrated	Basic	Extensive	Extensive

Educational Resources

Apple Education

• Everyone Can Code AR lessons
• Swift Playgrounds AR tutorials
• Developer education sessions
• University partnerships

Certification and Training

• Apple Developer Program resources
• Third-party training courses
• Online tutorials and workshops
• Community-driven learning

Enterprise Applications

RealityKit is increasingly used in enterprise contexts:

• Manufacturing visualization
• Remote assistance applications
• Training simulations
• Product configuration tools
• Architectural walkthroughs

Research and Development

Apple continues to invest in RealityKit research:

• Advanced rendering techniques
• Machine learning integration
• Improved physics simulation
• Enhanced realism
• Performance optimization

Known Issues and Workarounds

Common challenges developers face:

• Memory management in complex scenes
• Network latency in collaborative sessions
• Device-specific performance variations
• Asset optimization requirements

Future Roadmap

While Apple doesn't publicly share detailed roadmaps, trends suggest focus on:

• Enhanced AI integration
• Improved collaborative features
• Advanced simulation capabilities
• Better cross-platform tools
• Expanded device support

External Links

• Official RealityKit Documentation
• RealityKit Overview - Apple Developer
• Apple Augmented Reality Portal