Agent Skills: Apple SwiftUI iOS Design Best Practices

Apple SwiftUI iOS Design Best Practices

A builder's guide for implementing Apple-quality iOS interfaces in SwiftUI, grounded in two foundational design texts:

• Ken Kocienda — Creative Selection (empathy for the user, craft in coding, taste in choosing the best solution, demo culture of iterative refinement)
• John Edson — Design Like Apple (systems thinking, the product is the marketing, design out loud, design with conviction)

Contains 62 rules across 8 principle-based categories. Each rule identifies a specific anti-pattern, grounds the fix in a named principle, and provides the correct iOS 26 / Swift 6.2 SwiftUI implementation.

Scope & Relationship to Sibling Skills

This skill is the building and implementation guide — it teaches how to construct new SwiftUI interfaces from scratch using Apple-quality patterns. When loaded alongside ios-ui-refactor (reviewing/refactoring existing UI), this skill covers the greenfield implementation that ios-ui-refactor later audits. Use this skill for building new screens; use the sibling for evaluating and improving existing ones.

Clinic Architecture Contract (iOS 26 / Swift 6.2)

All guidance in this skill assumes the clinic modular MVVM-C architecture:

• Feature modules import Domain + DesignSystem only (never Data, never sibling features)
• App target is the convergence point and owns DependencyContainer, concrete coordinators, and Route Shell wiring
• Domain stays pure Swift and defines models plus repository, *Coordinating, ErrorRouting, and AppError contracts
• Data owns SwiftData/network/sync/retry/background I/O and implements Domain protocols
• Read/write flow defaults to stale-while-revalidate reads and optimistic queued writes
• ViewModels call repository protocols directly (no default use-case/interactor layer)

When to Apply

Reference these guidelines when:

• Building new SwiftUI views and screens from scratch
• Choosing between semantic colors, system typography, and spacing grids (Edson's Systems Thinking)
• Managing state with @State, @Binding, @Observable, @Environment (Kocienda's Craft)
• Selecting the right component: List vs LazyVStack, Sheet vs FullScreenCover (Kocienda's Taste)
• Composing views with @ViewBuilder, custom modifiers, and value types (Kocienda's Creative Selection)
• Implementing navigation with NavigationStack, TabView, sheets (Edson's Conversation)
• Laying out content with stacks, grids, frames, and adaptive layouts (Edson's Design Out Loud)
• Ensuring VoiceOver, touch targets, Dark Mode, and reduce motion support (Kocienda's Empathy)
• Adding transitions, loading states, and animation polish (Edson's Product Is the Marketing)

Rule Categories by Priority

| Priority | Category | Principle | Impact | Prefix | Rules | |----------|----------|-----------|--------|--------|-------| | 1 | Empathy in Every Pixel | Kocienda "Empathy" · Edson "Design Is About People" | CRITICAL | empathy- | 8 | | 2 | The Visual System | Edson "Systems Thinking" · Kocienda "Convergence" | CRITICAL | system- | 8 | | 3 | Craft: State as Foundation | Kocienda "Craft" | CRITICAL | craft- | 7 | | 4 | Creative Composition | Kocienda "Creative Selection" | HIGH | compose- | 6 | | 5 | Taste: The Right Choice | Kocienda "Taste" · Edson "Design with Conviction" | HIGH | taste- | 8 | | 6 | Navigation as Conversation | Edson "Design Is a Conversation" · Kocienda "The Demo" | HIGH | converse- | 9 | | 7 | Design Out Loud: Layout | Edson "Design Out Loud" · Kocienda "Intersection" | HIGH | layout- | 8 | | 8 | The Product Speaks | Edson "Product Is the Marketing" · Kocienda "Demo Culture" | MEDIUM | product- | 8 |

Quick Reference

1. Empathy in Every Pixel (CRITICAL)

Kocienda: "Empathy — trying to see the world from other people's perspectives." Edson: design begins with the person holding the device.

• empathy-semantic-colors - Use semantic colors, never hard-coded values
• empathy-dark-mode - Support Dark Mode from day one
• empathy-foreground-style - Use foregroundStyle over foregroundColor
• empathy-safe-areas - Always respect safe areas for content
• empathy-voiceover-labels - Add VoiceOver labels to every interactive element
• empathy-touch-targets - Ensure 44x44 point minimum touch targets
• empathy-reduce-motion - Always provide reduce motion fallback
• empathy-readable-width - Constrain text to readable width on iPad

2. The Visual System (CRITICAL)

Edson: "Zoom out to see relationships between objects." Kocienda: convergence — many decisions narrowing toward one coherent whole.

• system-typography - Use system typography styles, never fixed sizes
• system-visual-hierarchy - Establish clear visual hierarchy through size, weight, and color
• system-spacing-grid - Use a 4pt base unit for all spacing
• system-material-backgrounds - Use material backgrounds for depth and layering
• system-sf-symbols - Use SF Symbols for consistent iconography
• system-gradients - Apply gradients for visual depth, not decoration
• system-standard-margins - Use system standard margins consistently
• system-stack-config - Configure stack alignment and spacing explicitly

3. Craft: State as Foundation (CRITICAL)

Kocienda: "Craft — applying skill to achieve a high-quality result."

• craft-state-local - Use @State for view-local value types
• craft-state-binding - Use @Binding for child view mutations
• craft-state-environment - Use @Environment for shared app-wide data
• craft-state-observable - Use @Observable for model classes
• craft-avoid-body-state - Never create state inside the view body
• craft-minimize-scope - Minimize state scope to reduce re-renders
• craft-state-bindable - Use @Bindable for @Observable bindings

4. Creative Composition (HIGH)

Kocienda: "Creative selection — great software is built through composition and recombination."

• compose-body-some-view - Return some View from body, never concrete types
• compose-custom-properties - Use properties to make views configurable
• compose-modifier-order - Apply view modifiers in the correct order
• compose-viewbuilder - Use @ViewBuilder for flexible slot-based composition
• compose-prefer-value-types - Prefer value types for view data
• compose-prefer-composition - Prefer composition over inheritance for view reuse

5. Taste: The Right Choice (HIGH)

Kocienda: "Taste — refined judgment, the ability to choose the one right solution." Edson: commit to one approach and perfect it.

• taste-list-vs-lazyvstack - Choose List for system features, LazyVStack for custom layouts
• taste-sheet-vs-fullscreen - Choose sheet for tasks, fullScreenCover for immersion
• taste-picker - Choose the right picker style for the data type
• taste-grid-vs-lazygrid - Choose Grid for aligned data, LazyVGrid for scrollable collections
• taste-button - Use button styles that match the action's importance
• taste-textfield - Configure text input with the right keyboard and content type
• taste-alerts - Use alerts only for critical, blocking information
• taste-action-sheets - Use confirmation dialogs for contextual multi-choice actions

6. Navigation as Conversation (HIGH)

Edson: "Design is a conversation between the product and the person." Kocienda: demos as conversations about whether the interface speaks clearly.

• converse-navigationstack - Use NavigationStack for programmatic, type-safe navigation
• converse-tabview - Organize app sections with TabView for parallel navigation
• converse-sheet-item - Use item binding for data-driven sheet presentation
• converse-dismiss - Use environment dismiss for modal closure
• converse-toolbar - Place toolbar items in the correct semantic positions
• converse-tab-bar - Use tab bar for top-level section navigation
• converse-nav-bar - Configure navigation bar to communicate context
• converse-hierarchy - Design clear navigation hierarchy before writing code
• converse-search - Integrate search with the searchable modifier

7. Design Out Loud: Layout (HIGH)

Edson: "Design Out Loud — prototype relentlessly until layout feels inevitable." Kocienda: the intersection of technology and liberal arts.

• layout-stacks - Use stacks instead of manual positioning
• layout-spacer - Use Spacer for flexible space distribution
• layout-frame-sizing - Use frame() for explicit size constraints
• layout-zstack - Use ZStack for purposeful layered composition
• layout-grid - Use Grid for aligned non-scrolling tabular content
• layout-lazy-grids - Use LazyVGrid for scrollable multi-column layouts
• layout-adaptive - Use adaptive layouts for different size classes
• layout-scroll-indicators - Show scroll indicators for long scrollable content

8. The Product Speaks (MEDIUM)

Edson: "The product itself is the marketing." Kocienda: every animation and loading state built to survive Steve Jobs' scrutiny.

• product-transitions - Use semantic transitions for appearing views
• product-loading-states - Show honest loading states, not indefinite spinners
• product-with-animation - Use withAnimation for explicit state-driven animation
• product-matched-geometry - Use matchedGeometryEffect for contextual origin transitions
• product-list-cells - Design list cells with standard layouts
• product-content-unavailable - Use ContentUnavailableView for empty and error states
• product-segmented - Use segmented controls for visible, mutually exclusive options
• product-menus - Use menus for secondary actions without cluttering the interface

How to Use

Read individual reference files for detailed explanations and code examples:

• Section definitions - Category structure, principle sources, and impact levels
• Rule template - Template for adding new rules

Reference Files

| File | Description | |------|-------------| | references/_sections.md | Category definitions and principle grounding | | assets/templates/_template.md | Template for new rules | | metadata.json | Version and reference information |