ios-animation-code-review

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iOS Animation Code Review

iOS 动画代码审查

Quick Reference

快速参考

Issue Type	Reference
Spring parameters, withAnimation misuse, phase/keyframe bugs	references/swiftui-animation-patterns.md
Frame drops, offscreen rendering, main thread blocking	references/performance.md
Reduce Motion, VoiceOver, motion sensitivity	references/accessibility.md
Transition protocol, matchedGeometryEffect, navigation transitions	references/transitions.md

问题类型	参考文档
弹簧参数、withAnimation 误用、阶段/关键帧错误	references/swiftui-animation-patterns.md
掉帧、离屏渲染、主线程阻塞	references/performance.md
减少动态效果、VoiceOver、运动敏感度	references/accessibility.md
Transition 协议、matchedGeometryEffect、导航转场	references/transitions.md

Output Format

输出格式

Report each finding as:

[FILE:LINE] ISSUE_TITLE

Example:

[AnimatedCard.swift:42] Missing Reduce Motion fallback for spring animation

All details, code suggestions, and rationale follow after the header line.

每个问题报告格式如下：

[文件:行号] 问题标题

示例：

[AnimatedCard.swift:42] 弹簧动画缺少减少动态效果的降级方案

所有细节、代码建议及原理说明均在标题行之后列出。

Review Checklist

审查清单

```
@Environment(\.accessibilityReduceMotion)
```
checked — animations have Reduce Motion fallback
Animation is not the sole feedback channel — important state changes pair with haptics (
```
.sensoryFeedback
```
) or audio
Custom animation isn't duplicating system-provided motion (standard nav transitions, sheet presentation, SF Symbol effects)
Animations on frequent interactions are brief and unobtrusive — or absent (system handles it)
All animations are interruptible — user is never forced to wait for completion before interacting
Spring animations use
```
duration
```
/
```
bounce
```
parameters (not raw mass/stiffness/damping unless UIKit/CA)
No deprecated
```
.animation()
```
without
```
value:
```
parameter
```
withAnimation
```
wraps state changes, not view declarations
```
matchedGeometryEffect
```
IDs are stable and unique within the namespace
```
geometryGroup()
```
used when parent geometry animates with child views appearing
Looping animations (
```
PhaseAnimator
```
,
```
symbolEffect
```
) have finite phases or appropriate trigger
No
```
CATransaction.setAnimationDuration()
```
in UIView-backed layers (use UIView.animate instead)
Interactive animations handle interruption (re-trigger mid-flight doesn't break state)
Shadow animations provide explicit
```
shadowPath
```
(avoids per-frame recalculation)
Gesture-driven animations preserve velocity on release for natural completion
Gesture-driven feedback follows spatial expectations (dismiss direction matches reveal direction)
No animation of
```
.id()
```
modifier (destroys view identity — use
```
transition
```
or
```
matchedGeometryEffect
```
instead)

已检查
```
@Environment(\.accessibilityReduceMotion)
```
—— 动画具备减少动态效果的降级方案
动画并非唯一反馈渠道 —— 重要状态变更搭配触觉反馈（
```
.sensoryFeedback
```
）或音频
自定义动画未重复系统提供的动效（标准导航转场、弹窗展示、SF Symbol 效果）
频繁交互场景下的动画简洁且不突兀 —— 或直接由系统处理
所有动画均可中断 —— 用户无需等待动画完成即可进行交互
弹簧动画使用
```
duration
```
/
```
bounce
```
参数（除非是 UIKit/CA 场景，否则不使用原始的 mass/stiffness/damping 参数）
无未指定
```
value:
```
参数的废弃
```
.animation()
```
用法
```
withAnimation
```
包裹状态变更逻辑，而非视图声明
```
matchedGeometryEffect
```
的 ID 在命名空间内稳定且唯一
父级几何动画伴随子视图出现时已使用
```
geometryGroup()
```
循环动画（
```
PhaseAnimator
```
、
```
symbolEffect
```
）具备有限阶段或合适的触发条件
UIView 托管的图层中未使用
```
CATransaction.setAnimationDuration()
```
（改用 UIView.animate）
交互式动画可处理中断（中途重新触发不会破坏状态）
阴影动画提供了明确的
```
shadowPath
```
（避免逐帧重新计算）
手势驱动的动画在释放时保留速度，以实现自然完成效果
手势驱动的反馈符合空间预期（关闭方向与展示方向一致）
未对
```
.id()
```
修饰器执行动画（会破坏视图标识 —— 改用
```
transition
```
或
```
matchedGeometryEffect
```
）

When to Load References

何时加载参考文档

Incorrect spring setup or
```
withAnimation
```
scope issues → swiftui-animation-patterns.md
Hitches, dropped frames, or expensive animations in scroll views → performance.md
Missing Reduce Motion handling or motion accessibility → accessibility.md
```
matchedGeometryEffect
```
glitches or custom
```
Transition
```
bugs → transitions.md

弹簧设置错误或
```
withAnimation
```
作用域问题 → swiftui-animation-patterns.md
卡顿、掉帧或滚动视图中的高开销动画 → performance.md
缺少减少动态效果处理或动效可访问性问题 → accessibility.md
```
matchedGeometryEffect
```
异常或自定义
```
Transition
```
错误 → transitions.md

Review Questions

审查问题

Does every animation have a Reduce Motion fallback that preserves the information conveyed? Is animation the only feedback channel, or are haptics/audio supplementing it?
Is this custom animation necessary, or does the system already provide it (standard transitions, SF Symbol effects, Liquid Glass)?
Could this animation cause frame drops — is it animating expensive properties (blur, shadow without path, mask) in a list or scroll view?
Are all animations interruptible? Can the user act without waiting for completion? Does gesture-driven feedback follow spatial expectations?
Is
```
withAnimation
```
scoped to the minimal state change needed, or is it wrapping unrelated mutations?
For
```
matchedGeometryEffect
```
— are source and destination using the same ID and namespace, and is only one visible at a time?

每个动画是否都有保留信息传递的减少动态效果降级方案？动画是唯一反馈渠道，还是有触觉/音频作为补充？
这个自定义动画是否必要，还是系统已提供对应的动效（标准转场、SF Symbol 效果、Liquid Glass）？
该动画是否会导致掉帧 —— 是否在列表或滚动视图中对高开销属性（模糊、无路径的阴影、蒙版）执行动画？
所有动画是否均可中断？用户无需等待完成即可操作吗？手势驱动的反馈是否符合空间预期？
```
withAnimation
```
的作用域是否仅限于所需的最小状态变更，还是包裹了无关的修改操作？
对于
```
matchedGeometryEffect
```
—— 源端和目标端是否使用相同的 ID 和命名空间，且同一时间仅显示其中一方？