Core Animation Reference

Search these docs to answer questions about Core Animation (the QuartzCore framework). Use this skill when working directly with CALayer, layer-backed UIKit/AppKit views, explicit keyframe or spring animations on layer properties, particle systems, or per-frame callbacks via CADisplayLink.

For SwiftUI's declarative animation API (withAnimation, Animation, .animation(_:value:), transitions), use Apple's swiftui-specialist skill (its animations reference) instead. For SwiftUI immediate-mode drawing, use swiftui/canvas.md and swiftui/graphicscontext.md.

Return Format

Always include:

1. Summary — answer the question concisely.
2. File paths — list relevant files for full details, e.g.:
   • calayer.md for layer geometry, contents, hierarchy
   • cabasicanimation.md for animating a single property between two values
   • catransaction.md for batching, disabling implicit animations, or changing default duration

Files

When to Reach for Core Animation

• You need to animate a layer property SwiftUI/UIKit doesn't expose declaratively (e.g., CAGradientLayer.colors, CAShapeLayer.strokeEnd, CAEmitterLayer.birthRate).
• You need explicit keyframe or spring control with timing functions (CAMediaTimingFunction) per segment.
• You want to batch implicit animations off (CATransaction.setDisableActions(true)).
• You need a CADisplayLink per-frame callback (custom drawing loops, scrubbing, physics).
• You're rendering thousands of particles with CAEmitterLayer or replicating sublayers with CAReplicatorLayer.

If your problem fits inside withAnimation { ... } in SwiftUI or UIView.animate { ... } in UIKit, prefer those — Core Animation sits underneath both and is rarely the right starting point in 2026-era code.

Fetching More Docs

1. Search this skill's local .md files first.
2. If the topic is not here, check the other installed Apple skills, then grep their local files.
3. If no installed skill has the page, the QuartzCore path on Apple's site is /documentation/quartzcore/<symbol> — fetch via the sosumi.ai Markdown mirror (e.g. https://sosumi.ai/documentation/quartzcore/camediatimingfunction) or by running pnpm fetch-doc against the apple-skills tooling.