Swift UI

swift-ui

SwiftUI implementation patterns for building distinctive iOS and macOS interfaces.

Scope

This skill covers SwiftUI implementation—the views, modifiers, state management, and patterns needed to build polished native apps. For design theory (typography, color, hierarchy), see design-principles. For App Store submission, see design-review.

Routing

Based on what you're building, I'll reference the appropriate implementation guide:

View Composition

When: Building views, applying modifiers, structuring components Reference: references/views.md

• View composition patterns
• Modifier ordering
• Custom view modifiers
• ViewBuilder and generics

State Management

When: Managing data flow, handling state Reference: references/state.md

• Property wrappers (@State, @Binding, @StateObject, etc.)
• Data flow patterns
• Observable objects
• Environment values

Layout Patterns

When: Creating layouts, grids, responsive design Reference: references/layout.md

• Stack patterns (VStack, HStack, ZStack)
• LazyStacks and LazyGrids
• GeometryReader and layout priorities
• Adaptive layouts

Animation

When: Adding motion, transitions, gestures Reference: references/animation.md

• Implicit vs explicit animation
• Transitions
• Spring animations
• Gesture-driven animation

Accessibility

When: VoiceOver, Dynamic Type, accessibility Reference: references/accessibility.md

• Accessibility modifiers
• VoiceOver optimization
• Dynamic Type support
• Accessibility traits and actions

Architecture (No MVVM)

When: App structure, data flow patterns, questioning if you need ViewModels Reference: references/architecture.md

• Views as pure state expressions
• Environment for dependency injection
• .task(id:) and .onChange() as mini reducers
• SwiftData direct-in-view patterns
• Testing strategies without ViewModels

Data Persistence (SwiftData)

When: Storing data locally, Core Data replacement, iOS 17+ Reference: references/swiftdata.md

• @Model macro for defining entities
• @Query for reactive data fetching in views
• ModelContainer and ModelContext setup
• Relationships, predicates, migrations
• Direct SwiftUI integration (no ViewModel layer)

Quick Reference

Essential Patterns

// MARK: - View Composition

struct ContentView: View {
    var body: some View {
        NavigationStack {
            List(items) { item in
                ItemRow(item: item)
            }
            .navigationTitle("Items")
        }
    }
}

// MARK: - State Management (No ViewModel needed)

struct ItemDetailView: View {
    @Environment(APIClient.self) private var client
    @Environment(\.dismiss) private var dismiss
    @State private var item: Item?

    var body: some View {
        Form {
            // content
        }
        .task { await loadItem() }
    }
}

// MARK: - Animation

Button("Animate") {
    withAnimation(.spring(response: 0.3, dampingFraction: 0.6)) {
        isExpanded.toggle()
    }
}

HIG Quick Reference

Color System

// Use semantic colors
Color.primary       // Adapts to dark mode
Color.secondary
Color.accentColor
Color(uiColor: .systemBackground)
Color(uiColor: .secondarySystemBackground)

Anti-Patterns

• Force unwrapping in views
• Massive view bodies (extract into subviews, not ViewModels)
• Business logic in views (move to services in Environment)
• Ignoring @MainActor for UI updates
• Not supporting Dynamic Type
• Hardcoded colors instead of semantic
• Using ViewModels when @State + Environment suffices

Related Skills

• swift-lang - Swift language features (macros, concurrency, testing)
• design-principles - Theory behind the choices
• web-design - Web/CSS implementation
• design-review - App Store submission prep