Airbnb iOS Design System Best Practices

Opinionated, strict design system engineering for SwiftUI iOS 26 / Swift 6.2 apps. Contains 50 rules across 8 categories, prioritized by impact. Derived from Airbnb's Design Language System (DLS), Airbnb Swift Style Guide, Apple Human Interface Guidelines, and WWDC sessions. Mandates @Equatable on every view, @Observable for state, and style protocols as the primary component API.

Mandated Architecture Alignment

This skill is designed to work alongside swift-ui-architect. All code examples follow the same non-negotiable constraints:

• Feature modules depend on Domain + DesignSystem; no direct Data dependency
• @Observable for mutable UI state, ObservableObject / @Published never
• @Equatable macro on every view
• Style protocols as the primary component styling API (Airbnb DLS pattern)
• Asset catalog as the source of truth for color values
• Local SPM package for design system module boundary

Scope & Relationship to Sibling Skills

This skill is the infrastructure layer — it teaches how to BUILD the design system itself. When loaded alongside sibling skills: