SwiftUI Animation Reference

Comprehensive API reference for SwiftUI animation. Covers VectorArithmetic, Animatable protocol, @Animatable macro, animation types, zoom transitions, and UIKit bridging.

When to Use This Reference

Use this reference when you need:

• Understanding VectorArithmetic and Animatable requirements
• @Animatable macro usage (iOS 26+)
• Animation type options (spring, timing curves)
• Zoom transition implementation
• UIKit/AppKit animation bridging
• Custom animation algorithms

For debugging: See swiftui-debugging for animation issues.

Example Prompts

Questions you can ask Claude that will draw from this reference:

• "Why can't I animate an Int property?"
• "How do I use the @Animatable macro in iOS 26?"
• "What's the difference between Animation.spring and Animation.bouncy?"
• "How do I implement a zoom navigation transition?"
• "How do I use SwiftUI animations with UIView?"
• "What is VectorArithmetic and why does it matter?"

What's Covered

VectorArithmetic Protocol

• Required operations for interpolation
• Built-in conforming types (CGFloat, Double, CGPoint, etc.)
• Why Int can't be animated
• Creating custom animatable types

Animatable Protocol (iOS 13+)

• animatableData property requirement
• AnimatablePair for multiple values
• Manual conformance patterns

@Animatable Macro (iOS 26+)

• Automatic animatableData synthesis
• @AnimatableIgnored for excluded properties
• When to use macro vs manual conformance

Animation Types

• Spring animations (default since iOS 17)
• Timing curves (linear, easeIn, easeOut, easeInOut)
• Custom timing with UnitCurve
• Higher-order animations (repeatForever, delay)

Transaction System

• withAnimation and explicit animations
• Scoped animations (iOS 17+)
• Transaction customization

Zoom Transitions (iOS 18+)

• NavigationTransition.zoom
• matchedTransitionSource modifier
• Full-screen zoom presentations

UIKit/AppKit Bridging (iOS 18+)

• animate(with:) for UIView
• Applying SwiftUI animation curves to UIKit
• Gesture-driven animations

Performance

• Off-main-thread rendering
• Complex shape optimization
• When to use drawingGroup

Key Pattern

Custom Animatable Type

// iOS 13-25: Manual conformance
struct GradientPosition: Animatable {
    var startX: CGFloat
    var startY: CGFloat

    var animatableData: AnimatablePair<CGFloat, CGFloat> {
        get { AnimatablePair(startX, startY) }
        set {
            startX = newValue.first
            startY = newValue.second
        }
    }
}

// iOS 26+: Automatic with macro
@Animatable
struct GradientPosition {
    var startX: CGFloat
    var startY: CGFloat
    @AnimatableIgnored var name: String  // Not animated
}

Animation Types

// Default spring (iOS 17+)
.animation(.spring, value: isExpanded)

// Bouncy spring
.animation(.bouncy, value: isExpanded)

// Smooth spring
.animation(.smooth, value: isExpanded)

// Timing curve
.animation(.easeInOut(duration: 0.3), value: isExpanded)

Zoom Transition

// Source view
Image(item.image)
    .matchedTransitionSource(id: item.id, in: namespace)

// Destination with zoom
NavigationStack {
    DetailView()
}
.navigationTransition(.zoom(sourceID: item.id, in: namespace))

Documentation Scope

This page documents the axiom-swiftui-animation-ref reference skill—comprehensive animation API coverage Claude uses when you need specific animation implementation details.

For debugging: See swiftui-debugging for animation-related issues.

Related

• swiftui-debugging — View update and animation debugging
• swiftui-performance — Animation performance optimization

Resources

WWDC: 2023-10156 (Animate with springs), 2024-10145 (Enhance your animations), 2025-256 (SwiftUI 26)

Docs: /swiftui/animation, /swiftui/animatable