SpriteKit

Complete guide to building reliable SpriteKit games. Covers the scene graph model, physics engine, action system, game loop, rendering optimization, and integration with SwiftUI and Metal.

When to Use

Use this skill when:

• Building a new SpriteKit game or interactive simulation
• Implementing physics (collisions, contacts, forces, joints)
• Setting up game architecture (scenes, layers, cameras)
• Optimizing frame rate or reducing draw calls
• Implementing touch/input handling in a game
• Managing scene transitions and data passing
• Integrating SpriteKit with SwiftUI or Metal
• Debugging physics contacts that don't fire

Example Prompts

• "I'm building a SpriteKit platformer, how should I structure the scenes?"
• "My physics contacts aren't firing — what's wrong?"
• "How do I organize layers with a camera node?"
• "What's the correct way to handle touch in SpriteKit?"
• "My frame rate is dropping, how do I optimize?"
• "How do I integrate SpriteKit with SwiftUI?"
• "Objects are passing through walls in my game"

What This Skill Provides

Scene Graph Model

• Bottom-left origin coordinate system (opposite of UIKit)
• Anchor point mechanics for sprites and scenes
• Node tree hierarchy with z-ordering layers
• Camera node pattern for viewport control and HUD

Physics Engine

• Bitmask discipline (the #1 source of SpriteKit bugs)
• PhysicsCategory struct pattern for named bitmasks
• Contact detection with delegate pattern
• Body types: dynamic volume, static volume, edge
• Tunneling prevention with precise collision detection
• Forces vs impulses for movement

Actions System

• Sequencing, grouping, and repeating actions
• Named actions for cancellation and management
• Timing modes (linear, easeIn, easeOut, easeInEaseOut)
• Critical rule: never use actions on physics-controlled nodes

Performance Optimization

• Debug overlays (showsFPS, showsNodeCount, showsDrawCount)
• Texture atlas batching for reduced draw calls
• SKShapeNode trap (1 draw call per instance, unbatchable)
• Object pooling for frequently spawned objects
• Offscreen node removal

Game Loop

• 8-phase frame cycle understanding
• Delta time with spiral-of-death clamping
• Pause handling

Anti-Patterns

• Default bitmasks (0xFFFFFFFF)
• Missing contactTestBitMask
• Actions fighting physics
• SKShapeNode for gameplay sprites
• Strong self capture in action closures

Code Review Checklist

• 14-item verification covering physics, actions, performance, and scene management

Pressure Scenarios

• Physics contacts deadline debugging
• Frame rate denial
• SKShapeNode sunk cost

Related

• SpriteKit API Reference — Complete API tables for all node types, physics, actions, textures, and particles
• SpriteKit Diagnostics — Decision trees for 7 common SpriteKit symptoms
• spritekit-auditor — Automated scanning for SpriteKit anti-patterns