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SwiftUI animation patterns including springs, transitions, PhaseAnimator, KeyframeAnimator, SF Symbol effects, scroll-driven effects, mesh gradients, text renderers, and shader effects. Use when implementing, reviewing, or fixing animation or visual-effect code on iOS/macOS.
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SOC 職業分類に基づく
TDD and testing skills for iOS/macOS apps. Covers characterization tests, TDD workflows, test contracts, snapshot tests, test infrastructure, and deterministic quality gates (fitness functions, coverage ratchet, mutation testing). Use for test-driven development, adding tests to existing code, or building test infrastructure.
Set up SwiftUI visual regression testing with swift-snapshot-testing. Generates snapshot test boilerplate and CI configuration. Use for UI regression prevention.
Gate test coverage with a ratchet — a committed baseline that coverage may never drop below and only ever rises. Ships a coverage-gate script (xccov-based) plus an advisory CRAP report (complexity × uncovered). Use when agent-written code needs a deterministic "tests were actually written" check.
Enforce complexity and size limits on Swift code with SwiftLint threshold rules — cyclomatic complexity, function/type/file length, parameter count — adopted via a violations baseline so existing code never blocks. Use when agent-written code needs deterministic size constraints.
Swift language patterns and best practices including concurrency, performance, and modern idioms. Use for Swift language-level code review or architecture guidance.
Write architecture fitness functions — deterministic tests that enforce a project's hard rules (module boundaries, offline guarantees, content contracts) from inside its own test target. Use when a constraint lives only in prose (CLAUDE.md, code review) and should become un-arguable.
| name | animation-patterns |
| description | SwiftUI animation patterns including springs, transitions, PhaseAnimator, KeyframeAnimator, SF Symbol effects, scroll-driven effects, mesh gradients, text renderers, and shader effects. Use when implementing, reviewing, or fixing animation or visual-effect code on iOS/macOS. |
| allowed-tools | ["Read","Glob","Grep"] |
| last_verified | "2026-07-16T00:00:00.000Z" |
| review_by | "2027-06-22T00:00:00.000Z" |
| os_version | iOS 27 / macOS 27 |
Correct API shapes and patterns for SwiftUI animations. Prevents the most common mistakes: mixed spring parameter generations, wrong PhaseAnimator/KeyframeAnimator closure signatures, and using matchedGeometryEffect where matchedTransitionSource is needed.
Use this skill when the user:
scrollTransition, visualEffect)colorEffect, distortionEffect, layerEffect)Choose the right reference file based on what the user needs:
What are you animating?
│
├─ A state change (opacity, position, color)
│ └─ → core-animations.md
│ ├─ withAnimation { } — explicit animation
│ ├─ .animation(_:value:) — implicit animation
│ └─ Spring configuration — .spring, .bouncy, .snappy, .smooth
│
├─ A multi-step / sequenced animation
│ └─ → phase-keyframe-animators.md (PhaseAnimator)
│ └─ Cycles through discrete phases automatically or on trigger
│
├─ A complex multi-property animation (scale + rotation + offset)
│ └─ → phase-keyframe-animators.md (KeyframeAnimator)
│ └─ Timeline-based keyframes with per-property tracks
│
├─ A view appearing / disappearing
│ └─ → transitions.md
│ ├─ .transition() — insertion/removal
│ ├─ .contentTransition() — text/symbol changes
│ └─ .asymmetric() — different in/out
│
├─ A hero / zoom navigation transition
│ └─ → transitions.md (matchedTransitionSource section)
│ ├─ iOS 18+: matchedTransitionSource + .navigationTransition(.zoom)
│ ├─ UIKit: preferredTransition = .zoom (capture stable IDs, never views)
│ └─ iOS 14+: matchedGeometryEffect (NOT for NavigationStack)
│
├─ A UIKit view driven by SwiftUI state or gestures
│ └─ → transitions.md (Bridging UIKit and SwiftUI Animations)
│ └─ UIView.animate(.spring(...)) / context.animate in updateUIView
│
├─ An SF Symbol animation
│ └─ → symbol-effects.md
│ └─ .symbolEffect(.bounce), .pulse, .wiggle, .breathe, .rotate
│
├─ A scroll-driven, geometry-driven, or shader effect
│ └─ → visual-effects.md
│ ├─ .scrollTransition — carousel scale/parallax/caption fades
│ ├─ .visualEffect — position-based effects without GeometryReader
│ ├─ MeshGradient — animatable multi-point gradients
│ ├─ TextRenderer — per-line / per-glyph text animation
│ └─ ShaderLibrary + .colorEffect / .distortionEffect / .layerEffect
│
└─ Spring physics / timing configuration
└─ → core-animations.md (Spring Configurations section)
| API | Minimum Version | Reference |
|---|---|---|
withAnimation | iOS 13 | core-animations.md |
.animation(_:value:) | iOS 13 | core-animations.md |
.spring(response:dampingFraction:) | iOS 13 | core-animations.md |
.matchedGeometryEffect | iOS 14 | transitions.md |
.transition(.push(from:)) | iOS 16 | transitions.md |
.contentTransition(.numericText()) | iOS 16 | transitions.md |
PhaseAnimator | iOS 17 | phase-keyframe-animators.md |
KeyframeAnimator | iOS 17 | phase-keyframe-animators.md |
.spring(duration:bounce:) | iOS 17 | core-animations.md |
Spring presets (.bouncy, .snappy, .smooth) | iOS 17 | core-animations.md |
withAnimation(_:completionCriteria:_:completion:) | iOS 17 | core-animations.md |
.symbolEffect() | iOS 17 | symbol-effects.md |
.transition(.blurReplace) | iOS 17 | transitions.md |
.contentTransition(.symbolEffect(.replace)) | iOS 17 | transitions.md |
Transition protocol / TransitionPhase | iOS 17 | transitions.md |
TransactionKey, scoped .animation / .transaction variants | iOS 17 | core-animations.md |
KeyframeTimeline, .mapCameraKeyframeAnimator | iOS 17 | phase-keyframe-animators.md |
.scrollTransition, .visualEffect | iOS 17 | visual-effects.md |
Shaders: .colorEffect / .distortionEffect / .layerEffect | iOS 17 | visual-effects.md |
MeshGradient | iOS 18 | visual-effects.md |
TextRenderer / TextAttribute | iOS 18 | visual-effects.md |
.matchedTransitionSource | iOS 18 | transitions.md |
.navigationTransition(.zoom) — push, sheet, fullScreenCover | iOS 18 | transitions.md |
UIViewController.preferredTransition = .zoom | iOS 18 | transitions.md |
UIView.animate(_: Animation) / context.animate | iOS 18 | transitions.md |
| # | Mistake | Fix | Details |
|---|---|---|---|
| 1 | spring(response:bounce:) — mixing parameter generations | Use either spring(response:dampingFraction:) (iOS 13) or spring(duration:bounce:) (iOS 17) | core-animations.md |
| 2 | .animation(.spring()) without value: parameter | Always pass value: — the no-value variant is deprecated (iOS 15) | core-animations.md |
| 3 | Wrong PhaseAnimator closure signature | PhaseAnimator(phases) { content, phase in } — not { phase in } | phase-keyframe-animators.md |
| 4 | Using matchedGeometryEffect for NavigationStack transitions | Use matchedTransitionSource + .navigationTransition(.zoom) on iOS 18+ | transitions.md |
| 5 | Using withAnimation for SF Symbol effects | Use .symbolEffect() modifier instead | symbol-effects.md |
When reviewing animation code, verify:
AccessibilityMotionEffect or UIAccessibility.isReduceMotionEnabled; provide non-motion alternatives.animation(.spring()) without value: is deprecated; .animation(nil) is replaced by withTransactionresponse with bounce)withAnimation(_:completionCriteria:_:completion:) (iOS 17+), not inventing .onAnimationCompleted.transition() only affects views inside if/switch controlled by state; not for views that are always presentcontent closures, visualEffect closures, TextRenderer.draw, and Animatable view bodies run every frame; no allocation, formatting, or layout math inside| File | Content |
|---|---|
| core-animations.md | withAnimation, springs, completions, transactions + TransactionKey, timing curves, Animatable mechanics, fluid-interface principles (momentum projection, rubber-banding, hysteresis) |
| phase-keyframe-animators.md | PhaseAnimator, KeyframeAnimator, KeyframeTimeline, MapKit camera keyframes, custom animations |
| transitions.md | View transitions, custom Transition protocol, matched geometry, navigation/zoom transitions (SwiftUI + UIKit), interruptibility, UIKit↔SwiftUI bridging, gesture-driven springs |
| symbol-effects.md | SF Symbol effects, accessibility |
| visual-effects.md | scrollTransition, visualEffect, MeshGradient, TextRenderer, shader effects (colorEffect/distortionEffect/layerEffect), effect pipelines, semantic alignment guides |