dot-skills — Airbnb iOS SwiftUI Animations Best Practices

Opinionated, strict animation craft guide for SwiftUI iOS 26 / Swift 6.2 apps. Contains 50 rules across 8 categories, prioritized by impact. Derived from Airbnb Engineering motion patterns, Apple WWDC sessions, and Apple Human Interface Guidelines. Mandates @Equatable on every animated view, motion tokens for all spring/timing values, and design system tokens for layout.

Mandated Architecture Alignment

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

• @Equatable macro on every view (Airbnb measured 15% scroll hitch reduction)
• @Observable for complex animation state that involves business logic triggers
• @State for view-owned animation state (toggle booleans, drag offsets)
• Design system tokens: Spacing.xs/sm/md/lg, Radius.sm/md/lg — zero hardcoded layout numbers
• Motion tokens: Motion.standard/responsive/playful — zero scattered spring literals
• Semantic colors: .backgroundSurface, .accentPrimary — no raw Color literals in views
• Feature animations remain presentation-only; data/network concerns stay in Data package

Scope & Relationship to Sibling Skills

This skill is the motion layer — it teaches how to BUILD fluid, performant animations. When loaded alongside sibling skills: