Implement Apple HIG Interaction Patterns

Compiles Apple's Human Interface Guidelines interaction and UX patterns into eight synthesized Key Principles, a seven-row Pattern Selection Guide mapping user goals to recommended patterns, and full Apple reference docs for twenty-five patterns spanning onboarding, data entry, feedback, file management, notifications, multitasking, media playback, printing, ratings, search, settings, undo and redo, and workouts. The principles set the governing UX philosophy: minimize modality, reserving it for when attention is critical, a task must be completed or abandoned, or saving is essential; give every action visible, audible, or haptic feedback; prefer undo over confirmation dialogs for destructive actions, since undo is "almost always better than 'Are you sure?'"; launch quickly with a launch screen that transitions seamlessly rather than a splash screen; defer sign-in so people can explore before creating an account, supporting Sign in with Apple and passkeys; cap onboarding at three skippable screens taught through progressive disclosure; and respect user attention by consolidating notifications and never using them for marketing. The Pattern Selection Guide translates these into concrete choices: a first-run experience should be brief onboarding plus progressive disclosure, not long tutorials or mandatory sign-up; waiting for content should use skeleton screens or progress indicators, not blocking spinners with no context; confirming a destructive action should lean on undo support rather than repeated confirmation dialogs; and permission requests should be contextual and just-in-time rather than all requested at launch.

Use it when designing a specific interaction flow - onboarding, permission requests, drag-and-drop, file management, notifications, search, settings organization, undo/redo, or media playback - and you want the Apple-recommended pattern plus its common pitfalls. It complements rather than replaces hig-foundations (the accessibility, color, typography, and privacy principles underlying every pattern), hig-platforms (platform-specific implementations of these same patterns), and hig-components-layout/hig-components-content (the structural and content components a pattern is built from). It is a pattern-selection guide, not implementation code - the Output Format calls for a recommended pattern with rationale, a step-by-step implementation across each screen or state, platform variations, and common pitfalls, rather than a ready-to-paste snippet.

There is no API - output is a recommended pattern with rationale citing the relevant reference file, a step-by-step implementation plan covering each screen or state, platform variations for the targeted platforms, and a list of common pitfalls that violate HIG for that pattern. Before recommending, the skill asks where in the app the pattern appears and what surrounds it, which platforms are targeted, whether the flow is new or an improvement to an existing one, and whether it involves sensitive actions like destructive operations, payments, or permissions.

References specific Apple frameworks and APIs where its underlying docs name them - SKStoreReviewController for ratings prompts, Core Haptics and UIFeedbackGenerator for haptic patterns, HealthKit for workout data, and SharePlay for collaborative sharing - and cross-references three sibling HIG skills (hig-foundations, hig-platforms, hig-components-layout/hig-components-content) since interaction patterns depend on foundational and structural guidance to implement correctly.

Designers and developers implementing a specific app flow - onboarding, permissions, notifications, undo, search, settings, or media playback - on a native Apple platform, who want Apple's recommended pattern and its known pitfalls rather than designing the flow from first principles.