Apple Design System & Human Interface Guidelines (HIG)

This skill equips AI coding agents with the exact principles, visual specifications, component architectures, typography metrics, color tokens, motion curves, and automated compliance auditing defined by Apple's Human Interface Guidelines (HIG) across iOS, iPadOS, macOS, watchOS, visionOS, and modern Apple-grade Web UI.

🎯 Operational Modes

Mode 1 — Design & Build from Scratch

When tasked with creating new screens, apps, or web interfaces in Apple style:

Choose the platform-native navigation paradigm (e.g. Bottom Tab Bar for iOS, Sidebar for macOS/iPad, Ornaments for visionOS).
Establish the 8pt spatial grid and continuous squircle curvature (
```
G2 continuity
```
).
Apply the SF Pro / New York typography scale with optical tracking rules.
Implement semantic Dynamic Colors (Light & OLED Dark mode) and Liquid Frosted Glass materials.
Apply Apple spring physics (
```
cubic-bezier(0.25, 1, 0.5, 1)
```
) and tactile active feedback (
```
scale(0.97)
```
).

Mode 2 — Apple HIG Compliance Audit & Scoring

When reviewing an existing codebase, mockup, or component:

Run the audit tool
```
node skills/apple-design/scripts/audit-apple-design.mjs
```
to perform automated static scanning with a 0–100 Scoring Rubric.
Perform exact mathematical WCAG contrast checks and 44×44pt touch-target validations.
Fill out the Apple HIG Audit Scorecard across the 5 core pillars.
Deliver prioritized findings with Confidence Tagging:
- 🟢 Tool-verified: Statistically measured via CLI tool (e.g., contrast ratio, button dimension, static CSS rules).
- 🟡 Needs device test: Requires hardware interaction (e.g., Dynamic Type at 300%, Reduce Transparency toggle, VoiceOver speech hierarchy).
- 🔴 Assumed: Contextual design trade-off or subjective aesthetic evaluation.

🛠️ The Apple HIG Compliance CLI Engine

The built-in audit engine (

skills/apple-design/scripts/audit-apple-design.mjs

) provides four subcommands:

bash

# 1. Full Codebase Static Scan with 0-100 Scorecard (Default)
npm run audit
# or: node skills/apple-design/scripts/audit-apple-design.mjs [path]

# 2. WCAG Relative Luminance Contrast Ratio Check
node skills/apple-design/scripts/audit-apple-design.mjs contrast "#8E8E93" "#FFFFFF"
# -> Contrast Ratio: 3.26:1 [🔴 FAILED - Needs >= 4.5:1]

# 3. Tap Target Sizing Validation (44x44 pt minimum)
node skills/apple-design/scripts/audit-apple-design.mjs target 32 32
# -> Tap Target: 32x32 pt [🔴 FAILED - Minimum 44x44 pt]

# 4. Batch JSON Automated Verification
node skills/apple-design/scripts/audit-apple-design.mjs batch audit.json

Audit Scoring Rubric:

Base score: 100 points.
Point deduction: -10 points per violation.
Scorecard Classification:
- 🟢 90 – 100 pts: Ship (Sẵn sàng phát hành) — Đạt chuẩn xuất sắc.
- 🟡 70 – 89 pts: Cần sửa trước khi release (Fix before release) — Cần khắc phục trước khi đưa lên App Store / production.
- 🔴 < 70 pts: Cần thiết kế lại (Systematic redesign required) — Vi phạm nghiêm trọng kiến trúc hoặc khả năng tiếp cận.

1. Core Design Philosophy

Apple interfaces are built upon three primary pillars:

Clarity:
- Text is legible at every size; icons are precise, distinct, and universally understood.
- Adornments are subtle and purposeful. Content always takes visual priority over decorative Chrome.
- Negative space (whitespace) provides breathing room and clarifies visual hierarchy.
Deference:
- Fluid motion, translucent materials, and crisp typography elevate content without competing with it.
- Backgrounds defer to content; chrome recedes when the user is engaged in primary tasks.
Depth:
- Distinct visual layers, realistic lighting, specular highlights, and physical spring physics convey spatial hierarchy and tactile realism.
- Elevations and materials communicate interactive affordances without harsh dropped shadows or abrasive outlines.

2. Universal Apple Design Tenets & Critical Rules

🚫 Forbidden Anti-Patterns (Never Do These)

NO Purple/Violet On Dark Themes: Never use purple fonts or violet accent buttons on dark backgrounds. Use Apple System Blue (
```
#0A84FF
```
) or semantic system tints.
NO Harsh Drop Shadows: Never use dense black un-diffused box shadows (
```
box-shadow: 0 4px 10px rgba(0,0,0,0.5)
```
). Use multi-layered ambient diffusion (
```
box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.04)
```
).
NO Sharp / Geometric Corners: Never leave interactive controls, cards, or inputs with 0px radius or arbitrary non-continuous corners.
NO Untracked Large Typography: Never render large headings (>24px) without tight letter-spacing (-0.02em to -0.03em / -0.5px to -1.2px).
NO Non-Standard Touch Targets: Never create clickable elements smaller than 44×44 pt (iOS standard) or 28×28 pt (macOS compact pointer).
NO Plain Static CSS Transitions: Never use
```
ease-in-out
```
for physical UI interactions; always use fluid spring physics or Apple easing curves.

3. Visual Foundations

A. Typography System (San Francisco & New York)

Primary Interface Font: SF Pro (

-apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Helvetica Neue", sans-serif

)

Monospace Font: SF Mono (

ui-monospace, "SF Mono", Menlo, Monaco, Consolas, monospace

)

Serif Font: New York (

"New York", ui-serif, Georgia, Cambria, serif

)

Typographic Scale & Optical Sizing Rules:

Style	Size (pt/px)	Weight	Line Height	Tracking / Letter Spacing
Large Title	34px	Bold (700)	41px	`-0.022em (-0.75px)`
Title 1	28px	Bold / SemiBold	34px	`-0.020em (-0.56px)`
Title 2	22px	Bold / SemiBold	28px	`-0.018em (-0.40px)`
Title 3	20px	SemiBold (600)	25px	`-0.015em (-0.30px)`
Headline	17px	SemiBold (600)	22px	`-0.012em (-0.20px)`
Body	17px	Regular (400)	22px	`-0.010em (-0.17px)`
Callout	16px	Regular (400)	21px	`-0.008em (-0.13px)`
Subheadline	15px	Regular (400)	20px	`-0.005em (-0.08px)`
Footnote	13px	Regular (400)	18px	`0.000em (0.00px)`
Caption 1	12px	Regular (400)	16px	`0.005em (+0.06px)`
Caption 2	11px	Regular / Medium	13px	`0.010em (+0.11px)`

4. Materials, Translucency & Specular Glass

Apple materials blur underlying content to create visual grounding while maintaining vibrancy:

css

/* Authentic Apple Ultra-Thin Frosted Glass Material */
.apple-material-ultrathin {
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: blur(20px) saturate(190%);
  -webkit-backdrop-filter: blur(20px) saturate(190%);
  border: 1px solid rgba(255, 255, 255, 0.45);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.04), 0 1px 2px rgba(0, 0, 0, 0.02);
}

@media (prefers-color-scheme: dark), [data-theme="dark"] {
  .apple-material-ultrathin {
    background: rgba(28, 28, 30, 0.75);
    backdrop-filter: blur(25px) saturate(190%);
    -webkit-backdrop-filter: blur(25px) saturate(190%);
    border: 1px solid rgba(255, 255, 255, 0.12);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.35), 0 1px 3px rgba(255, 255, 255, 0.05) inset;
  }
}

5. Animation Physics (Apple Spring Curves)

Never use linear or standard ease curves for interactive UI. Use authentic Apple spring physics:

Spring Parameters Reference:

Interactive / Tap feedback:

mass: 1, stiffness: 350, damping: 35

(CSS approx:

cubic-bezier(0.25, 1, 0.5, 1)

)

Sheet Presentation / Modal Slide:

mass: 1.2, stiffness: 280, damping: 28