# HIG: Motion

Source: [Apple HIG — Motion](https://developer.apple.com/design/human-interface-guidelines/motion)

## Best Practices

- Add motion **purposefully** — don't add for its own sake
- Make motion **optional** — never the only way to communicate information
- Supplement visual feedback with haptics and audio alternatives
- Liquid Glass responds differently to touch (more emphasis) vs trackpad (more subdued)

## Feedback

- Strive for **realistic** feedback following gestures and expectations
- Aim for **brevity and precision** — succinct animations convey info without distraction
- Avoid adding motion to **frequently used UI interactions** — system handles standard animations
- Let people **cancel motion** — don't force waiting for animations to complete
- Consider **animated SF Symbols** (SF Symbols 5+)

## Accessibility

- If `accessibilityReduceMotion` is enabled, replace large motion with **opacity crossfades**
- Non-negotiable for accessibility compliance

## visionOS Motion

- Avoid motion at edges of field of view — peripheral motion causes discomfort
- For large moving objects, increase translucency or lower contrast
- Use **fades** to relocate objects (fade out, move, fade in)
- Avoid letting people rotate virtual worlds — disrupts stability
- Provide a **stationary frame of reference** — contained movement is more comfortable
- Avoid sustained oscillation (especially ~0.2 Hz)

## watchOS

- SwiftUI provides streamlined motion APIs
- All layout/appearance animations include **built-in easing** (can't customize)

## Design Principles

1. Motion should **reinforce understanding** of how something works
2. **Brief and precise** over prominent and elaborate
3. Let system handle standard interaction animations
4. Custom animation for **unique moments** only (reveals, transitions, celebrations)
5. Always respect Reduce Motion accessibility setting