swiftui-advanced

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SwiftUI Advanced

SwiftUI 高级进阶

Advanced SwiftUI patterns for gesture composition, adaptive layouts, architecture decisions, and performance optimization.

适用于手势组合、自适应布局、架构决策和性能优化的高级SwiftUI模式。

Reference Loading Guide

参考资料加载指南

ALWAYS load reference files if there is even a small chance the content may be required. It's better to have the context than to miss a pattern or make a mistake.

Reference	Load When
Gestures	Composing multiple gestures, GestureState, custom recognizers
Adaptive Layout	ViewThatFits, AnyLayout, size classes, iOS 26 free-form windows
Architecture	MVVM vs TCA decision, State-as-Bridge, property wrapper selection
Performance	Instruments 26, view body optimization, unnecessary updates

只要有哪怕一点点可能需要用到相关内容，就一定要加载参考文件。 拥有上下文总比遗漏模式或犯错要好。

参考资料	加载时机
手势	组合多个手势、GestureState、自定义识别器
自适应布局	ViewThatFits、AnyLayout、尺寸类、iOS 26 自由形态窗口
架构	MVVM vs TCA 决策、State-as-Bridge、属性包装器选择
性能	Instruments 26、视图体优化、不必要的更新

Core Workflow

核心工作流程

Identify pattern category from user's question
Load relevant reference for detailed patterns and code examples
Apply pattern following the decision trees and anti-patterns
Verify using provided checklists or profiling guidance

从用户问题中识别模式类别
加载相关参考资料以获取详细模式和代码示例
遵循决策树和反模式应用对应模式
使用提供的检查清单或性能分析指南进行验证

Decision Trees

决策树

Gesture Composition

手势组合

Both gestures at same time? ->
```
.simultaneously
```
One must complete before next? ->
```
.sequenced
```
Only one should win? ->
```
.exclusively
```

需要同时触发两个手势？ ->
```
.simultaneously
```
必须完成一个手势才能触发下一个？ ->
```
.sequenced
```
只能有一个手势生效？ ->
```
.exclusively
```

Layout Adaptation

布局适配

Pick best-fitting variant? ->
```
ViewThatFits
```
Animated H/V switch? ->
```
AnyLayout
```
Need actual dimensions? ->
```
onGeometryChange
```

需要选择最适合的布局变体？ ->
```
ViewThatFits
```
需要在横向/纵向布局间切换并带动画？ ->
```
AnyLayout
```
需要获取实际尺寸？ ->
```
onGeometryChange
```

Architecture Selection

架构选择

Small app, Apple patterns? -> @Observable + State-as-Bridge
Complex presentation logic? -> MVVM with @Observable
Rigorous testability needed? -> TCA

小型应用，遵循Apple官方模式？ -> @Observable + State-as-Bridge
复杂的展示逻辑？ -> 搭配@Observable的MVVM
需要严格的可测试性？ -> TCA

Common Mistakes

常见误区

Gesture composition order matters —
```
.simultaneously
```
and
```
.sequenced
```
have different trigger timing. Swapping them silently changes behavior. Understand gesture semantics before using.
ViewThatFits over-used — ViewThatFits remeasures on every view change. For animated H/V switches, use
```
AnyLayout
```
instead. Use ViewThatFits only for static variant selection.
onGeometryChange triggering unnecessary updates — Reading geometry changes geometry, which triggers updates, which changes geometry... circular. Use
```
.onGeometryChange
```
only with proper state management to avoid loops.
Architecture mismatch mid-project — Starting with @Observable + State-as-Bridge then realizing you need TCA is expensive. Choose architecture upfront based on complexity (small app = @Observable, complex = TCA).
Ignoring view body optimization — Computing expensive calculations in view body repeatedly kills performance. Move calculations to properties or models. Profile with Instruments 26 before optimizing prematurely.

手势组合的顺序至关重要 —
```
.simultaneously
```
和
```
.sequenced
```
的触发时机不同。交换它们的顺序会悄无声息地改变行为。在使用前务必理解手势的语义。
过度使用ViewThatFits — ViewThatFits会在每次视图变化时重新测量。对于横向/纵向布局的动画切换，应使用
```
AnyLayout
```
替代。仅在选择静态布局变体时使用ViewThatFits。
onGeometryChange触发不必要的更新 — 读取几何信息会改变几何结构，进而触发更新，反过来又改变几何信息……形成循环。仅在配合恰当的状态管理时使用
```
.onGeometryChange
```
，以避免循环。
项目中途更换架构 — 先采用@Observable + State-as-Bridge，之后才发现需要TCA，这种转换成本很高。应根据项目复杂度提前选择架构（小型应用 = @Observable，复杂应用 = TCA）。
忽略视图体优化 — 在视图体中反复执行昂贵的计算会严重影响性能。将计算逻辑移至属性或模型中。在过早优化前，先使用Instruments 26进行性能分析。