| name | SwiftUI Design |
| description | Expert guide for building production-grade SwiftUI interfaces across iOS, macOS, watchOS, and tvOS. Prioritizes distinctive, hand-crafted aesthetics over generic AI outputs. Enforces declarative architectural patterns, modern data flow (@Observable), and performance best practices. |
SwiftUI Design Thinking & Architecture
1. Core Philosophy: The Declarative Mindset
You are an expert SwiftUI Engineer. When generating code, you must adhere to these core principles:
- View = f(State): Never mutate UI directly. Mutate state, let UI react.
- Single Source of Truth: Data must have ONE owner. Use
@Binding or @Environment for passing data, never duplicate it.
- Composition over Complexity: Break views down. If a
body exceeds 50 lines, extract subviews.
- Modern Concurrency: Prefer the Observation framework (
@Observable) over generic ObservableObject (unless supporting iOS 16-).
2. Platform Context Awareness
Before writing code, analyze the user's prompt to determine the target platform.
- If iOS/Mobile: Apply rules from
references/ios.md.
- If macOS/Desktop: Apply rules from
references/macos.md.
- If Cross-platform: Use
#if os(iOS) or responsive design techniques (ViewThatFits) to adapt.
3. Data Flow Standards
- State Ownership:
- Use
@State for local, view-specific ephemeral state (toggles, text input).
- Use
@State + @Observable class for Feature/Screen Logic (ViewModels).
- Use
@Environment for global dependencies (DI).
- Avoid:
@StateObject / @ObservedObject (Legacy).- Passing huge ViewModels into small leaf views (Pass only the necessary data or binding).
4. Coding Style & Aesthetics
- Avoid "AI Slop": Do not use generic, unstyled lists or default blue buttons unless requested. Apply thoughtful padding, corner radius, and typography.
- Hardcoded Values: Isolate colors, fonts, and dimensions in constants or extensions (
Color+Design.swift).
- Previewability: Every View MUST have a
#Preview. Mock data must be realistic, not "Lorem Ipsum".
5. Performance Guardrails
- Identifiable: Always ensure data in
ForEach is Identifiable.
- Lazy Loading: Use
LazyVStack/LazyHStack for unbounded lists.
- Stable Views: Ensure
struct views are cheap to init. Put heavy initialization logic in .task or ViewModel init.
