The most 'methodology-focused' layer of Apple's design system — it does not talk about which component to use, but about why. Design philosophy (why Human Interface is called Human · design serves people · 6 qualities of great design) + 12 core design principles (Wayfinding / Feedback / Visibility / Consistency / Mental Model / Proximity / Grouping / Mapping / Affordance / Progressive Disclosure / 80-20 / Symmetry) + 5 elements of Intentional Design (radical simplification / deep understanding / extreme focus / personal connection / direct communication) + Fluid Interfaces (dynamic motion vs timed animation · elastic physics · projected momentum · 6 sub-principles) + complete workflow from concept to interface (structure → navigation → content → visuals, with a vinyl record App hands-on example) + multisensory design (sound design · 3 haptic principles · transient/continuous · technical constraints) + multilingual, intelligence and ML experiences (data/metrics · system intelligence journey) + 60-minute rapid prototyping.
The source of the modern Apple HIG and even the entire field of graphical interface design — two historic classic PDFs. The 1987 *Apple Human Interface Guidelines: The Apple Desktop Interface* (164 pages, the first official HIG) put forward 10 human interface principles; the 1992 *Macintosh Human Interface Guidelines* (418 pages, complete 11-chapter edition) expanded them to 12. The 12 principles: Metaphors / Direct Manipulation / See-and-Point (noun-then-verb) / Consistency / WYSIWYG / User Control / Feedback and Dialog / Forgiveness / Perceived Stability / Aesthetic Integrity / Modelessness / Knowledge of Your Audience. Plus principles of graphic communication (visual consistency / simplicity / clarity). Bilingual. These principles established in 1987 remain the root of [[apple-hig-design-principles]] today.
16 curated articles from the Nielsen Norman Group Human-Computer Interaction (HCI) knowledge base. Coverage spans three major sections: ① Hard laws of motor control and cognition — Fitts's Law (time to reach a target T depends on distance D and target width W; larger targets are faster · screen edges = infinite targets · padded targets · Woodworth two-phase movement model · distance comparison of linear vs rectangular vs pie menus · place buttons close to the prior action), Accot-Zhai Steering Law (movement time within a bounded path T=a+b·A/W; narrower and longer paths are harder · L-shaped corridors in hierarchical menus · vector triangle buffer zones · Mega Menus · forgiving paths), Touch Targets (minimum 1cm×1cm / 0.4in · average finger width 1.6–2cm · thumb 2.5cm · spacing to prevent accidental taps · View-Tap Asymmetry · use larger 2cm targets for children/older adults/one-handed use), design process (Iterative design +38% per round · Parallel design merge +70%, then iterate for 152% · Competitive testing). ② Interaction patterns and interfaces — State-Switch controls (dual control: state indicator + toggle button vs single control · Mute button counterexample WebEx · positive example Zoom), Tutorials vs Contextual Help (push vs pull · short-term memory load · progressive disclosure), Task Analysis (task vs goal · contextual inquiry · HTA hierarchical task analysis diagram · GOMS · cognitive complexity), four core Data Tables tasks (lookup/compare/edit single row/batch operations · freeze header and first column · zebra striping · in-place editing vs non-modal side panel). ③ Smart homes and new scenarios — 7 best practices for smart devices, 5 guidelines for onboarding and connection, 5 motivations for smart homes (convenience/peace of mind/saving money/useful data/ambience), 3 user types (Managers/Everyday Users/Restricted Users) + Zone×Role dual axis · agentic execution · invisibility of automation · ability to degrade to Dumb Work, 7 principles of smart notifications (timely/relevant/specific/intensity/frequency/channel/adjustable) × 3 types (Reactive/Proactive/Optimization), Smarts over Sentience (warm AI increases error rate by 10–30% · RAG), 13 practices for Virtual Queues, 10 guidelines for AR calibration. Audience = product managers; terms explained in-line, decision-oriented (when to use/how to choose/counterexamples).
