
swiftui-animation
Implement, diagnose, or review SwiftUI motion using explicit and scoped implicit animations, springs, transitions, PhaseAnimator, KeyframeAnimator, matched geometry or navigation zoom, SF Symbol effects, and custom Animation types. Use when views should animate on state changes, insertion, removal, navigation, or multi-step choreography, or when motion must respect Reduce Motion and Swift concurrency.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/dpearson2699/swift-ios-skills --skill swiftui-animation- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads swiftui-animation automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
Security audits
Independent scans of the skill's instructions and bundled files.
SKILL.md
The instructions your agent reads when the skill is triggered.
SwiftUI Animation (iOS 26+)
Review, write, and fix SwiftUI animations. Apply modern animation APIs with correct timing, transitions, and accessibility handling using Swift 6.3 patterns.
Contents
- Triage Workflow
- withAnimation (Explicit Animation)
- Implicit Animation
- Spring Type (iOS 17+)
- PhaseAnimator (iOS 17+)
- KeyframeAnimator (iOS 17+)
@Animatable Macro- matchedGeometryEffect (iOS 14+)
- Navigation Zoom Transition (iOS 18+)
- Transitions (iOS 17+)
- ContentTransition (iOS 16+)
- Symbol Effects (iOS 17+)
- Symbol Rendering Modes
- Common Mistakes
- Review Checklist
- References
Triage Workflow
Step 1: Identify the animation category
| Category | API | When to use |
|---|---|---|
| State-driven | withAnimation, .animation(_:body:), .animation(_:value:) | Explicit state changes, selective modifier animation, or simple value-bound changes |
| Multi-phase | PhaseAnimator | Sequenced multi-step animations |
| Keyframe | KeyframeAnimator | Complex multi-property choreography |
| Shared element | matchedGeometryEffect | Layout-driven hero transitions |
| Navigation | matchedTransitionSource + .navigationTransition(.zoom) | NavigationStack push/pop zoom |
| View lifecycle | .transition() | Insertion and removal |
| Text content | .contentTransition() | In-place text/number changes |
| Symbol | .symbolEffect() | SF Symbol animations |
| Custom | CustomAnimation protocol | Novel timing curves |
| Core Animation bridge | CALayer, CAAnimation, CADisplayLink | Read references/core-animation-bridge.md before advising |
Step 2: Choose the animation curve
.easeInOut(duration: 0.3) // mechanical timing
.smooth // fluid, no bounce
.snappy // responsive, small bounce
.bouncy // playful, visible bounce
.spring(duration: 0.5, bounce: 0.3)
Use the advanced catalog when presets do not express the intended motion.
Step 3: Apply and verify
- Confirm animation triggers on the correct state change.
- Test with Accessibility > Reduce Motion enabled.
- Verify no expensive work runs inside animation content closures.
- For CA bridges, use Coordinators for delegates, invalidate display links, treat frame-rate ranges as hints, and adapt work to the actual refresh rate.
withAnimation (Explicit Animation)
withAnimation(.spring) { isExpanded.toggle() }
// With completion (iOS 17+)
withAnimation(.smooth(duration: 0.35), completionCriteria: .logicallyComplete) {
isExpanded = true
} completion: { loadContent() }
Implicit Animation
Use withAnimation for state-mutation ownership, .animation(_:body:) for
selected modifiers, and .animation(_:value:) for simple value-bound changes.
Badge()
.foregroundStyle(isActive ? .green : .secondary)
.animation(.snappy) { content in
content
.scaleEffect(isActive ? 1.15 : 1.0)
.opacity(isActive ? 1.0 : 0.7)
}
Circle()
.scaleEffect(isActive ? 1.2 : 1.0)
.opacity(isActive ? 1.0 : 0.6)
.animation(.bouncy, value: isActive)
Spring Type (iOS 17+)
Prefer the perceptual form or a preset. Load the advanced reference only when physical, response-based, or settling parameters are required.
Spring(duration: 0.5, bounce: 0.3)
Spring.smooth
Spring.snappy
Spring.bouncy
PhaseAnimator (iOS 17+)
Cycle through discrete phases with per-phase animation curves.
enum PulsePhase: CaseIterable {
case idle, grow, shrink
}
struct PulsingDot: View {
var body: some View {
PhaseAnimator(PulsePhase.allCases) { phase in
Circle()
.frame(width: 40, height: 40)
.scaleEffect(phase == .grow ? 1.4 : 1.0)
.opacity(phase == .shrink ? 0.5 : 1.0)
} animation: { phase in
switch phase {
case .idle: .easeIn(duration: 0.2)
case .grow: .spring(duration: 0.4, bounce: 0.3)
case .shrink: .easeOut(duration: 0.3)
}
}
}
}
Trigger-based variant advances to the next phase on each trigger change:
PhaseAnimator(PulsePhase.allCases, trigger: tapCount) { phase in
// ...
} animation: { _ in .spring(duration: 0.4) }
KeyframeAnimator (iOS 17+)
Animate multiple properties along independent timelines.
struct AnimValues {
var scale: Double = 1.0
var yOffset: Double = 0.0
var opacity: Double = 1.0
}
struct BounceView: View {
@State private var trigger = false
var body: some View {
Button { trigger.toggle() } label: {
Image(systemName: "star.fill")
.font(.largeTitle)
.keyframeAnimator(
initialValue: AnimValues(),
trigger: trigger
) { content, value in
content
.scaleEffect(value.scale)
.offset(y: value.yOffset)
.opacity(value.opacity)
} keyframes: { _ in
KeyframeTrack(\.scale) {
SpringKeyframe(1.5, duration: 0.3)
CubicKeyframe(1.0, duration: 0.4)
}
KeyframeTrack(\.yOffset) {
CubicKeyframe(-30, duration: 0.2)
CubicKeyframe(0, duration: 0.4)
}
KeyframeTrack(\.opacity) {
LinearKeyframe(0.6, duration: 0.15)
LinearKeyframe(1.0, duration: 0.25)
}
}
}
.buttonStyle(.plain)
}
}
Keyframe types: LinearKeyframe (linear), CubicKeyframe (smooth curve),
SpringKeyframe (spring physics), MoveKeyframe (instant jump).
Use repeating: true for looping keyframe animations.
Swift 6: keyframe closures are @Sendable; capture state/env values before the modifier.
@Animatable Macro
Replaces manual AnimatableData boilerplate. Attach to any type with
animatable stored properties.
@Animatable
struct WaveShape: Shape {
var frequency: Double
var amplitude: Double
var phase: Double
@AnimatableIgnored var lineWidth: CGFloat
func path(in rect: CGRect) -> Path {
// draw wave using frequency, amplitude, phase
}
}
Rules:
- Stored properties must conform to
VectorArithmetic. - Use
@AnimatableIgnoredto exclude non-animatable properties. - Computed properties are never included.
matchedGeometryEffect (iOS 14+)
Synchronize geometry between views for shared-element animations.
struct HeroView: View {
@Namespace private var heroSpace
@State private var isExpanded = false
var body: some View {
Group {
if isExpanded {
Button {
withAnimation(.spring(duration: 0.4, bounce: 0.2)) {
isExpanded = false
}
} label: {
DetailCard()
.matchedGeometryEffect(id: "card", in: heroSpace)
}
} else {
Button {
withAnimation(.spring(duration: 0.4, bounce: 0.2)) {
isExpanded = true
}
} label: {
ThumbnailCard()
.matchedGeometryEffect(id: "card", in: heroSpace)
}
}
}
.buttonStyle(.plain)
}
}
Exactly one source view per ID should be visible; otherwise results are undefined.
Navigation Zoom Transition (iOS 18+)
Pair matchedTransitionSource on the source view with
.navigationTransition(.zoom(...)) on the destination.
struct GalleryView: View {
@Namespace private var zoomSpace
let items: [GalleryItem]
var body: some View {
NavigationStack {
ScrollView {
LazyVGrid(columns: [GridItem(.adaptive(minimum: 100))]) {
ForEach(items) { item in
NavigationLink {
GalleryDetail(item: item)
.navigationTransition(
.zoom(sourceID: item.id, in: zoomSpace)
)
} label: {
ItemThumbnail(item: item)
.matchedTransitionSource(
id: item.id, in: zoomSpace
)
}
}
}
}
}
}
}
Apply .navigationTransition on the destination view, not on inner containers.
Transitions (iOS 17+)
Control how views animate on insertion and removal.
if showBanner {
BannerView()
.transition(.move(edge: .top).combined(with: .opacity))
}
See All Transition Types
for the built-in catalog and custom Transition examples.
Asymmetric transitions:
.transition(.asymmetric(
insertion: .push(from: .bottom),
removal: .opacity
))
ContentTransition (iOS 16+)
Animate in-place content changes without insertion/removal.
Text("\(score)")
.contentTransition(.numericText(countsDown: false))
.animation(.snappy, value: score)
// For SF Symbols
Image(systemName: isMuted ? "speaker.slash" : "speaker.wave.3")
.contentTransition(.symbolEffect(.replace.downUp))
Types: .identity, .interpolate, .opacity,
.numericText(countsDown:), .numericText(value:), .symbolEffect.
Symbol Effects (iOS 17+)
Animate SF Symbols with semantic effects. .bounce, .pulse, .variableColor,
.scale, .appear, .disappear, and .replace are iOS 17+; .breathe,
.rotate, and .wiggle require iOS 18+.
// Discrete (triggers on value change)
Image(systemName: "bell.fill").symbolEffect(.bounce, value: notificationCount)
// iOS 18+
Image(systemName: "arrow.clockwise")
.symbolEffect(.wiggle.clockwise, value: refreshCount)
// Indefinite (active while condition holds)
Image(systemName: "wifi").symbolEffect(.pulse, isActive: isSearching)
// iOS 18+
Image(systemName: "mic.fill")
.symbolEffect(.breathe, isActive: isRecording)
// Variable color with chaining
Image(systemName: "speaker.wave.3.fill")
.symbolEffect(
.variableColor.iterative.reversing.dimInactiveLayers,
options: .repeating,
isActive: isPlaying
)
Scope: .byLayer, .wholeSymbol. Direction varies per effect.
Symbol Rendering Modes
Choose .monochrome, .hierarchical, .multicolor, or .palette with
.symbolRenderingMode(_:); use .foregroundStyle to supply palette colors.
Variable symbols: use Image(systemName:variableValue:) (iOS 16+) for percentage fill. Use .symbolVariableValueMode(_:) (iOS 26+) to choose .draw or .color.
Image(systemName: "wifi", variableValue: signalStrength) // 0.0...1.0
.symbolVariableValueMode(.draw) // iOS 26+
Docs: SymbolRenderingMode · symbolRenderingMode(_:) · Image(systemName:variableValue:) · symbolVariableValueMode(_:)
Common Mistakes
1. Using bare .animation(_:) when you need precise scope
// TOO BROAD — applies when the view changes
.animation(.easeIn)
.animation(.easeIn, value: isVisible) // CORRECT: value-bound
// CORRECT — scope animation to selected modifiers
.animation(.easeIn) { content in
content.opacity(isVisible ? 1.0 : 0.0)
}
withAnimation(.easeIn) { isVisible.toggle() } // CORRECT: own mutation
2. Expensive work or actor-isolated reads inside animation closures
keyframeAnimator / PhaseAnimator content closures run every frame. Precompute expensive values, animate only visual properties, and capture state/env values before @Sendable keyframe closures.
3. Missing reduce motion support
For symbols, remove inherited effects; gate larger motion with reduceMotion ? .none : animation.
@Environment(\.accessibilityReduceMotion) private var reduceMotion
Image(systemName: "wifi").symbolEffect(.pulse, isActive: isSearching).symbolEffectsRemoved(reduceMotion)
4. Multiple matchedGeometryEffect sources
Only one source view per ID should be visible at a time. Multiple visible sources with the same ID cause undefined layout.
5. Using DispatchQueue or UIView.animate
// WRONG
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { withAnimation { isVisible = true } }
// CORRECT
withAnimation(.spring.delay(0.5)) { isVisible = true }
6. Forgetting animation on ContentTransition
// WRONG — no animation, content transition has no effect
Text("\(count)").contentTransition(.numericText(countsDown: true))
// CORRECT — pair with animation
Text("\(count)")
.contentTransition(.numericText(countsDown: true))
.animation(.snappy, value: count)
7. navigationTransition on wrong view
Apply .navigationTransition(.zoom(sourceID:in:)) on the outermost destination view, not inside a container.
Review Checklist
- Animation curve matches intent (spring for natural, ease for mechanical)
-
withAnimationwraps the state change; implicit animation uses.animation(_:body:)for selective modifier scope or.animation(_:value:)with an explicit value -
matchedGeometryEffecthas exactly one source per ID; zoom uses matchingid/namespace -
@Animatablemacro used when synthesis fits; manualanimatableDatakept only when custom packing is clearer -
accessibilityReduceMotionchecked; noDispatchQueue/UIView.animate - Transitions use
.transition();contentTransitionis paired with animation and uses the narrowest implicit animation scope that fits - Animated state changes on @MainActor; animation-driving types are Sendable
References
- See references/animation-advanced.md for CustomAnimation protocol, Spring variants, Transition types, symbol effects, Transaction system, UnitCurve, and performance guidance; Core Animation bridging patterns: references/core-animation-bridge.md.
FAQ
What does the swiftui-animation skill do?
Implement, diagnose, or review SwiftUI motion using explicit and scoped implicit animations, springs, transitions, PhaseAnimator, KeyframeAnimator, matched geometry or navigation zoom, SF Symbol effects, and custom Animation types. Use when views should animate on state changes, insertion, removal, navigation, or multi-step choreography, or when motion must respect Reduce Motion and Swift concurrency.
How do I install swiftui-animation?
Run npx skills add https://github.com/dpearson2699/swift-ios-skills --skill swiftui-animation in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/swiftui-animation/ (personal) or .claude/skills/swiftui-animation/ (project).
Which AI agents can use swiftui-animation?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is swiftui-animation safe to install?
Security partners have reviewed it: Gen Agent Trust Hub passed; Socket passed; Snyk passed; Runlayer passed; ZeroLeaks passed. As with any skill, read the SKILL.md and bundled scripts before installing.
Who maintains swiftui-animation?
It is published by dpearson2699 in dpearson2699/swift-ios-skills. It has 5,454 recorded installs.
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