Agent Skills: Apple HIG SwiftUI iOS 26 / Swift 6.2 Best Practices

Apple HIG SwiftUI iOS 26 / Swift 6.2 Best Practices

A principal designer's lens for evaluating and refactoring SwiftUI interfaces to Apple-quality standards, grounded in Rams, Segall, and Edson. Contains 51 rules across 8 categories, each grounded in specific principles from three foundational design texts:

• Dieter Rams — Ten Principles for Good Design ("less, but better," "design should be honest")
• Ken Segall — Insanely Simple (simplicity as a core principle for intuitive, beautiful products)
• John Edson — Design Like Apple (design-focused culture, prototyping to perfection, the product is the marketing)

Categories are ordered by a visual review process: start with what to remove, then what to clarify, then what to make honest, invisible, systematic, thorough, enduring, and finally what to refine.

Scope & Relationship to Sibling Skills

This skill is the refactoring and review lens — it evaluates existing UI and identifies visual anti-patterns to fix. When loaded alongside ios-design (building new UI), ios-hig (HIG compliance), or swift-refactor (code-level refactoring), this skill supersedes overlapping rules with more detailed "incorrect -> correct" transformations and "When NOT to apply" guidance. Use this skill for auditing and improving existing screens; use the siblings for greenfield implementation.

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:

• Reviewing existing SwiftUI screens for visual quality issues
• Auditing whether every element on screen earns its place (Rams #10)
• Evaluating if the interface is self-explanatory without tooltips (Rams #4)
• Checking that colors, states, and hierarchy tell the truth (Rams #6)
• Ensuring animations and materials are invisible, not decorative (Rams #5)
• Verifying spacing, radii, and colors form a coherent system (Edson "Systems Thinking")
• Confirming edge cases — reduce motion, touch targets, safe areas — are handled (Rams #8)
• Adopting iOS 26 / Swift 6.2 APIs that refine previously impossible interactions (Edson "Design Out Loud")

Rule Categories by Priority

| Priority | Category | Principle | Impact | Prefix | Rules | |----------|----------|-----------|--------|--------|-------| | 1 | Less, But Better | Rams #10 + Segall "Think Minimal" | CRITICAL | less- | 7 | | 2 | Self-Evident Design | Rams #4 + Segall "Think Human" | CRITICAL | evident- | 6 | | 3 | Honest Interfaces | Rams #6 + Segall "Think Brutal" | CRITICAL | honest- | 6 | | 4 | Invisible Design | Rams #5 + Edson "Product Is Marketing" | HIGH | invisible- | 6 | | 5 | Systems, Not Pieces | Edson "Systems Thinking" + Rams #8 | HIGH | system- | 6 | | 6 | Thorough to the Last Detail | Rams #8 + Rams #2 | HIGH | thorough- | 7 | | 7 | Enduring Over Trendy | Rams #7 + Edson "Design With Conviction" | MEDIUM-HIGH | enduring- | 5 | | 8 | Refined Through Iteration | Edson "Design Out Loud" + Rams #1/#3 | MEDIUM | refined- | 8 |

Quick Reference

1. Less, But Better (CRITICAL)

Rams #10: "Good design is as little design as possible." Segall: Apple succeeded by saying no to a thousand things.

• less-single-focal - One primary focal point per screen
• less-type-restraint - Limit to 3-4 distinct type treatments per screen
• less-one-typeface - One typeface per app, differentiate with weight and size
• less-color-restraint - Reserve saturated colors for small interactive elements
• less-one-color-purpose - Each semantic color serves exactly one purpose
• less-purposeful-motion - Every animation must communicate state change or provide feedback
• less-fewer-controls - Remove controls that do not serve the core task

2. Self-Evident Design (CRITICAL)

Rams #4: "Good design makes a product understandable." Segall: interfaces must speak in terms people understand.

• evident-visual-weight - Combine size, weight, and contrast for hierarchy
• evident-whitespace-grouping - Use whitespace to separate conceptual groups
• evident-progressive-disclosure - Use progressive disclosure for dense information
• evident-reading-order - Align visual weight with logical reading order
• evident-navigation-intent - Sheets for tasks and creation, push for drill-down hierarchy
• evident-label-clarity - Use clear labels over ambiguous icons

3. Honest Interfaces (CRITICAL)

Rams #6: "Good design is honest." Segall: clarity without sugar-coating.

• honest-semantic-colors - Use semantic colors, never hard-coded black or white
• honest-contrast - Ensure WCAG AA contrast ratios
• honest-dark-mode - Define light and dark variants for every custom color
• honest-foreground-style - Use foregroundStyle over foregroundColor
• honest-depth-cues - Use materials for layering, not drop shadows for depth
• honest-loading-states - Show real progress, not indefinite spinners

4. Invisible Design (HIGH)

Rams #5: "Good design is unobtrusive." Edson: the product itself is the marketing.

• invisible-spring-physics - Default to spring animations for all UI transitions
• invisible-spring-presets - Use .smooth for routine, .snappy for interactive, .bouncy for delight
• invisible-no-easing - Prefer springs over linear and easeInOut for UI elements
• invisible-system-materials - Use system materials, not custom semi-transparent backgrounds
• invisible-symbol-effects - Use built-in symbolEffect, not manual symbol animation
• invisible-content-transitions - Use contentTransition for changing text and numbers

5. Systems, Not Pieces (HIGH)

Edson: "Design is systems thinking." Rams #8: nothing must be arbitrary or left to chance.

• system-spacing-grid - Use a 4pt base unit for all spacing
• system-consistent-padding - Use consistent padding across all screens
• system-corner-radii - Standardize corner radii per component type
• system-alignment - Consistent alignment per content type within a screen
• system-color-naming - Name custom colors by role, not hue
• system-brand-integration - Map brand palette onto iOS semantic color roles

6. Thorough to the Last Detail (HIGH)

Rams #8: "Care and accuracy in the design process show respect for the user." Rams #2: if the user cannot reliably use it, the product has failed.

• thorough-reduce-motion - Always provide reduce motion fallback
• thorough-touch-targets - All interactive elements at least 44x44 points
• thorough-safe-areas - Always respect safe areas
• thorough-readable-weights - Avoid light font weights for body text
• thorough-vibrancy-levels - Match vibrancy level to content importance
• thorough-material-thickness - Choose material thickness by contrast needs
• thorough-background-interaction - Enable background interaction for peek-style sheets

7. Enduring Over Trendy (MEDIUM-HIGH)

Rams #7: "Good design is long-lasting." Edson: commit to a voice that persists across product generations.

• enduring-system-text-styles - Use Apple text styles, never fixed font sizes
• enduring-weight-not-caps - Use weight for emphasis, not ALL CAPS
• enduring-swipe-back - Never break the system back-swipe gesture
• enduring-zoom-navigation - Use zoom transitions for collection-to-detail navigation
• enduring-card-modularity - Use self-contained cards for dashboard layouts

8. Refined Through Iteration (MEDIUM)

Edson: "Design out loud" — prototype relentlessly until every interaction feels inevitable. Rams #1: innovation serves genuine purpose.

• refined-scroll-transitions - Use scrollTransition for scroll-position visual effects
• refined-phase-animator - Use PhaseAnimator for multi-step animation sequences
• refined-mesh-gradients - Use MeshGradient for premium dynamic backgrounds
• refined-text-renderer - Use TextRenderer for hero text animations only
• refined-inspector - Use inspector for trailing-edge detail panels
• refined-multi-detent - Provide multiple sheet detents with drag indicator
• refined-matched-geometry - Use matchedGeometryEffect for contextual origin transitions
• refined-no-hard-cuts - Always animate between states, even minimally

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 |