Apple HIG Designer

A professional-grade frontend design skill that enables Claude Code to create interfaces following Apple's Human Interface Guidelines (HIG), achieving the quality standards of Apple's design team.

When to Use This Skill

Activate this skill when users request:

• Apple-style or iOS/macOS-style interfaces
• HIG-compliant UI components
• SF Symbols integration
• San Francisco typography implementation
• Modern glass effects (optional, user must explicitly request)

Trigger phrases:

• "Design an Apple-style..."
• "Create a HIG-compliant..."
• "iOS/macOS style component"
• "苹果风格的界面"
• "符合 HIG 的设计"

Core Design Principles

The Four Pillars of Apple Design

1. Clarity (清晰)
   • Every element has a purpose
   • Eliminate unnecessary complexity
   • Users understand immediately without instructions
   • Use clear visual hierarchy
2. Deference (尊重内容)
   • UI elements support, not compete with content
   • Minimize chrome and visual noise
   • Let content be the hero
   • Use subtle backgrounds and borders
3. Depth (层次)
   • Create clear visual hierarchy through layers
   • Use shadows, blur, and translucency purposefully
   • Motion reinforces spatial relationships
   • Z-axis communicates importance
4. Consistency (一致性)
   • Familiar patterns across platforms
   • Predictable interactions
   • Unified visual language
   • Respect platform conventions

Design System Specifications

Typography System

Font Family: San Francisco (SF Pro)

/* System Font Stack for Web */
:root {
  --font-system: -apple-system, BlinkMacSystemFont, 'SF Pro Display',
                 'SF Pro Text', 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SF Mono', SFMono-Regular, Menlo, Monaco, monospace;
}

/* Font Size Scale (iOS) */
--text-caption2: 11px;    /* Caption 2 */
--text-caption1: 12px;    /* Caption 1 */
--text-footnote: 13px;    /* Footnote */
--text-subhead: 15px;     /* Subheadline */
--text-body: 17px;        /* Body - Default */
--text-headline: 17px;    /* Headline (semibold) */
--text-title3: 20px;      /* Title 3 */
--text-title2: 22px;      /* Title 2 */
--text-title1: 28px;      /* Title 1 */
--text-large-title: 34px; /* Large Title */

Typography Rules:

• Use SF Pro Display for sizes ≥ 20pt
• Use SF Pro Text for sizes < 20pt
• Maintain consistent line-height (1.2-1.5)
• Use weight for hierarchy, not just size

Color System

/* Apple System Colors - Light Mode */
:root {
  /* Primary Colors */
  --system-blue: #007AFF;
  --system-green: #34C759;
  --system-indigo: #5856D6;
  --system-orange: #FF9500;
  --system-pink: #FF2D55;
  --system-purple: #AF52DE;
  --system-red: #FF3B30;
  --system-teal: #5AC8FA;
  --system-yellow: #FFCC00;

  /* Gray Scale */
  --system-gray: #8E8E93;
  --system-gray2: #AEAEB2;
  --system-gray3: #C7C7CC;
  --system-gray4: #D1D1D6;
  --system-gray5: #E5E5EA;
  --system-gray6: #F2F2F7;

  /* Semantic Colors */
  --label-primary: #000000;
  --label-secondary: rgba(60, 60, 67, 0.6);
  --label-tertiary: rgba(60, 60, 67, 0.3);
  --label-quaternary: rgba(60, 60, 67, 0.18);

  /* Backgrounds */
  --bg-primary: #FFFFFF;
  --bg-secondary: #F2F2F7;
  --bg-tertiary: #FFFFFF;

  /* Separators */
  --separator: rgba(60, 60, 67, 0.29);
  --separator-opaque: #C6C6C8;
}

/* Dark Mode */
@media (prefers-color-scheme: dark) {
  :root {
    --system-blue: #0A84FF;
    --system-green: #30D158;
    --system-indigo: #5E5CE6;
    --system-orange: #FF9F0A;
    --system-pink: #FF375F;
    --system-purple: #BF5AF2;
    --system-red: #FF453A;
    --system-teal: #64D2FF;
    --system-yellow: #FFD60A;

    --system-gray: #8E8E93;
    --system-gray2: #636366;
    --system-gray3: #48484A;
    --system-gray4: #3A3A3C;
    --system-gray5: #2C2C2E;
    --system-gray6: #1C1C1E;

    --label-primary: #FFFFFF;
    --label-secondary: rgba(235, 235, 245, 0.6);
    --label-tertiary: rgba(235, 235, 245, 0.3);
    --label-quaternary: rgba(235, 235, 245, 0.18);

    --bg-primary: #000000;
    --bg-secondary: #1C1C1E;
    --bg-tertiary: #2C2C2E;

    --separator: rgba(84, 84, 88, 0.6);
    --separator-opaque: #38383A;
  }
}

Spacing System

8pt Grid System:

:root {
  --space-1: 4px;   /* Extra small */
  --space-2: 8px;   /* Small */
  --space-3: 12px;  /* Medium-small */
  --space-4: 16px;  /* Medium */
  --space-5: 20px;  /* Medium-large */
  --space-6: 24px;  /* Large */
  --space-8: 32px;  /* Extra large */
  --space-10: 40px; /* 2X large */
  --space-12: 48px; /* 3X large */
}

Touch Target Requirements:

• iOS: Minimum 44×44 points
• visionOS: Minimum 60 points tap area
• Always add sufficient padding for small visual elements

Border Radius (Concentric Design)

:root {
  /* Base radius values */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-2xl: 24px;
  --radius-full: 9999px; /* Capsule */
}

/* Concentric Rule: inner_radius + padding = outer_radius */
/* Example: 8px inner + 8px padding = 16px outer */

Component Patterns

The following components should follow Apple HIG conventions. For complete CSS implementations, see resources/design-tokens.css and resources/ui-patterns.md. For React component examples, see resources/components.jsx.

Buttons

• Primary: Capsule shape (border-radius: 9999px), min-height: 44px, system-blue background, white text, 600 weight
• Secondary: Same capsule shape, system-blue text on rgba(0, 122, 255, 0.1) background
• Press feedback: scale(0.98) on :active

Glass Effect (Optional - Only When Requested)

• Only use when user explicitly requests glass/frosted effects
• Default designs should use solid backgrounds for readability and performance
• backdrop-filter: blur(20px) saturate(180%) with semi-transparent background
• Always provide non-glass fallback

Cards

• Default: Solid background (--bg-tertiary), border-radius: 16px, subtle box-shadow
• Grouped style: --bg-secondary outer with --bg-tertiary inner items, separated by --separator

Input Fields

• min-height: 44px, --bg-secondary background, border-radius: 12px
• Focus state: box-shadow: 0 0 0 4px rgba(0, 122, 255, 0.3)

Tab Bars

• Position fixed at bottom, height: 49px + safe-area padding
• Minimum 44x44pt touch targets per tab
• Always display text labels (never icon-only)
• Use filled SF Symbols for selected state, outline for unselected
• Support badge for notifications (red oval, white text)

Toolbars

• Three sections: leading (back/title), center (tools), trailing (actions)
• Maximum 3 item groups
• Use SF Symbols without borders
• Primary action uses .prominent style on trailing side
• Back button: circular with symbol only (no text)

Sheets

• Detents: large (100%), medium (50%)
• Include grabber indicator (36x5px, centered)
• Done button: top-right; Cancel button: top-left
• Semi-transparent backdrop rgba(0,0,0,0.4)

Alerts

• Use only for critical information (sparingly)
• Maximum 3 buttons; use specific verb titles, avoid "OK"
• Cancel: leading side; Destructive: only for unintended destructive actions
• Width: 270px, border-radius: 14px

Lists and Tables

• Minimum row height: 44px
• Info button: reveals details without navigation
• Disclosure indicator (>): navigates to subview
• Grouped style: 10px border-radius, inset separators start at 60px

Animation Guidelines

Timing Functions

:root {
  /* Apple's preferred easing */
  --ease-default: cubic-bezier(0.25, 0.1, 0.25, 1);
  --ease-in: cubic-bezier(0.42, 0, 1, 1);
  --ease-out: cubic-bezier(0, 0, 0.58, 1);
  --ease-in-out: cubic-bezier(0.42, 0, 0.58, 1);

  /* Spring-like easing */
  --ease-spring: cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

Duration Scale

:root {
  --duration-instant: 100ms;  /* Micro-interactions */
  --duration-fast: 200ms;     /* Hover, focus states */
  --duration-normal: 300ms;   /* Standard transitions */
  --duration-slow: 500ms;     /* Complex animations */
}

Interaction Feedback

/* Press feedback */
.interactive {
  transition: transform var(--duration-instant) var(--ease-out);
}

.interactive:active {
  transform: scale(0.97);
}

/* Hover glow */
.interactive:hover {
  box-shadow: 0 0 0 4px rgba(0, 122, 255, 0.15);
}

SF Symbols Integration

Rendering Modes

1. Monochrome: Single color for all layers
2. Hierarchical: Opacity variations for depth
3. Palette: Custom colors per layer
4. Multicolor: Apple's intrinsic symbol colors

Usage Guidelines

• Toolbar/Navigation: Use outline variant
• Tab Bar: Use fill variant
• Match text size: Symbols auto-align with SF font
• Provide text alternatives: Always include aria-label

Web Implementation (Icon Font Alternative)

<!-- Using SF Symbols via system font -->
<span class="sf-symbol" aria-label="Settings">􀣋</span>

<!-- Or use equivalent system icons -->
<svg class="icon" aria-hidden="true">
  <use href="#icon-gear"></use>
</svg>

Accessibility Requirements

Color Contrast

• Normal text: 4.5:1 minimum (WCAG AA)
• Large text: 3:1 minimum
• Interactive elements: Clearly distinguishable states

Motion

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

Semantic HTML

<!-- Always use semantic elements -->
<button type="button">Action</button>
<nav aria-label="Main navigation">...</nav>
<main role="main">...</main>

Output Format

When generating Apple-style UI code, always include:

1. Complete, runnable code (CSS/React/Vue)
2. Light/Dark mode support via CSS custom properties
3. Design rationale explaining HIG compliance
4. Responsive breakpoints for different devices
5. Accessibility attributes (aria-*, role, etc.)

Default Behavior

• Use solid backgrounds by default for better readability
• Glass/blur effects only when user explicitly requests
• Always provide non-glass fallback for browsers without backdrop-filter support

Example Output Structure

/**
 * Apple HIG Compliant Component
 *
 * Design Decisions:
 * - Uses SF Pro system font stack for native feel
 * - 44pt minimum touch target for accessibility
 * - Capsule shape for primary actions (HIG recommendation)
 * - Solid background for optimal readability
 * - Supports prefers-color-scheme for auto theming
 */

const AppleButton = ({ children, variant = 'primary', ...props }) => {
  return (
    <button
      className={`btn btn-${variant}`}
      {...props}
    >
      {children}
    </button>
  );
};

Best Practices Checklist

Before finalizing any design output, verify:

• Typography: Using SF Pro with correct size thresholds
• Colors: System colors with Light/Dark variants
• Spacing: Following 8pt grid
• Touch targets: Minimum 44×44pt
• Border radius: Concentric relationships maintained
• Animations: Using Apple-standard easing curves
• Accessibility: WCAG AA compliant, reduced motion support
• Consistency: Matches platform conventions
• Backgrounds: Solid by default, glass only when requested

Additional Resources

Local References (read these for detailed implementations)

• For complete design patterns and real-world examples, see REFERENCE.md
• For CSS custom properties and design tokens, see resources/design-tokens.css
• For React component templates, see resources/components.jsx
• For detailed UI pattern documentation, see resources/ui-patterns.md

External References

• Apple Human Interface Guidelines
• Apple Design Resources
• SF Symbols
• Apple Fonts

This skill ensures Claude Code produces interfaces that meet Apple's exacting design standards, creating cohesive, accessible, and beautiful user experiences.