iOS Animation Implementation

Write animation code that uses Apple's frameworks directly. Third-party animation libraries add dependency risk and often lag behind new OS releases — Apple's APIs are well-optimized for the render pipeline and get free improvements with each iOS version.

Before Writing Custom Animation

Check whether the system already handles the motion you need. Apple's HIG: "Many system components automatically include motion, letting you offer familiar and consistent experiences throughout your app." System components also automatically adjust for accessibility settings and input methods — Liquid Glass (iOS 26) responds with greater emphasis to direct touch and produces subdued effects for trackpad. Custom animation can't match this adaptiveness for free, so prefer system-provided motion when it exists.

Skip custom animation when:

• Standard navigation transitions cover your case (push, pop, sheet, fullScreenCover)
• SF Symbol .symbolEffect provides the feedback you need
• .contentTransition(.numericText) handles your data change
• The system's default spring on withAnimation is sufficient

Write custom animation when:

• The system doesn't provide the spatial relationship you need (hero transitions, custom gestures)
• You need coordinated multi-property choreography
• The animation is a signature moment that defines the app's identity
• Gesture-driven interaction requires custom progress mapping