SceneKit

Guide to maintaining existing SceneKit code and planning migration to RealityKit. SceneKit is soft-deprecated as of iOS 26 (no new features, only security patches). This skill covers the scene graph model, materials, physics, animation, SwiftUI integration, and a migration decision tree.

When to Use

Use this skill when:

• Maintaining existing SceneKit code
• Building a SceneKit prototype (with awareness of deprecation)
• Planning migration from SceneKit to RealityKit
• Debugging SceneKit rendering, physics, or animation issues
• Integrating SceneKit content with SwiftUI
• Loading 3D models via Model I/O or SCNSceneSource

Example Prompts

• "Should I start a new 3D project in SceneKit or RealityKit?"
• "How do I integrate SceneKit with SwiftUI now that SceneView is deprecated?"
• "What's the best way to migrate our SceneKit app to RealityKit?"
• "How do I set up PBR materials in SceneKit?"
• "My SceneKit physics contacts aren't working"
• "How do I convert .scn files to USDZ for RealityKit?"

What This Skill Provides

Deprecation Context

• SceneKit soft-deprecated as of iOS 26 (existing apps continue to work)
• SceneView (SwiftUI) formally deprecated -- UIViewRepresentable replacement pattern
• Apple's forward path is RealityKit

Scene Graph Architecture

• Right-handed Y-up coordinate system
• Transform hierarchy (parent-child cascading)
• SCNView (UIKit) and UIViewRepresentable (SwiftUI replacement)

Geometry and Materials

• Built-in geometry types (box, sphere, cylinder, plane, torus, capsule, cone, tube, text)
• PBR materials (diffuse, metalness, roughness, normal, AO, emission)
• Shader modifiers at 4 entry points (geometry, surface, lightingModel, fragment)

Animation

• SCNAction (declarative sequences, groups, repeats)
• Implicit animation (SCNTransaction)
• Explicit animation (CAAnimation bridge)
• Loading animations from files

Physics

• Body types (dynamic, static, kinematic), collision categories, contact delegate
• Category, collision, and contact test bitmasks

Asset Pipeline

• Supported formats (USDZ preferred, DAE, SCN, OBJ, Alembic)
• Converting .scn to USDZ via xcrun scntool

Migration Decision Tree

• New project, AR features, visionOS target, heavy investment, maintenance mode -- clear branching guidance

Anti-Patterns

• Starting new projects in SceneKit
• Using .scn files without USDZ conversion
• Deep shader modifier customization (zero portability to RealityKit)
• Relying on SCNRenderer for custom pipelines
• Ignoring deprecation warnings

Related

• SceneKit API Reference — Complete SceneKit API with RealityKit migration mapping for every major concept
• RealityKit — Apple's recommended 3D framework with ECS architecture
• RealityKit API Reference — RealityKit API for migration target reference