Generate Apple HIG Layout and Navigation Code

Compiles Apple's Human Interface Guidelines for layout and navigation components into eight synthesized Key Principles, a Navigation Pattern Selection table mapping six common app structures to their recommended pattern, and full Apple reference docs for twelve components: sidebars, column views, outline views, split views, tab views, tab bars, scroll views, windows, panels, lists and tables, boxes, and ornaments. The principles set the governing logic: organize hierarchically (sidebars for top-level sections, lists for browsable items, detail views for individual content), match navigation pattern to platform (tab bars for flat iPhone navigation between peer sections, sidebars for deep hierarchical iPad/Mac navigation), and prefer system navigation containers - UINavigationController, UISplitViewController, NavigationSplitView, TabView - for their built-in adaptivity, accessibility, and state restoration. The Navigation Pattern Selection table gives concrete recommendations: 3-5 peer top-level sections map to a Tab Bar (bottom tab bar on iPhone, sidebar via .sidebarAdaptable on iPadOS 18+, sidebar or toolbar tabs on Mac); deep hierarchical content maps to Sidebar plus NavigationSplitView (single-column stack on iPhone, two or three columns on iPad, full multi-column on Mac); a deep file or folder tree maps to a Finder-style Column View; a flat list with detail maps to a two-column Split View; document-based apps with inspectors map to Window plus Panels; and spatial apps with tools map to Window plus Ornaments on visionOS.

Use it when choosing an app's top-level navigation structure and layout hierarchy, and when verifying that structure adapts correctly across size classes and platforms. It comes with a six-item Layout Adaptation Checklist covering compact-width collapse on iPhone portrait, sidebar expansion on iPad landscape or Mac, behavior under every iPad multitasking split ratio and Slide Over, Dynamic Type and logical VoiceOver order, portrait/landscape reflow, and ergonomic window/ornament positioning on visionOS - each meant to be verified, not assumed. Two components are platform-specific: ornaments only apply on visionOS as toolbar attachments on windows, and Finder-style column views are a Mac-native pattern that adapts differently, or collapses to push navigation, on iPad and iPhone.

There is no API - output is a recommended navigation pattern with rationale tied to the app's information architecture, a layout hierarchy expressed root-down (for example TabView > NavigationSplitView > List > Detail), platform adaptation across the targeted platforms and size classes, and explicit size-class transition behavior. Inputs the skill asks for before recommending: the app's information architecture (section count, hierarchy depth), how many top-level sections exist, which platforms are targeted, whether iPad multitasking needs to be supported, and whether the implementation is SwiftUI or UIKit.

Names the concrete system container types behind each recommendation - UINavigationController and UISplitViewController in UIKit, NavigationSplitView and TabView in SwiftUI - and the iPadOS 18+ .sidebarAdaptable tab-bar-to-sidebar modifier. It cross-references four sibling HIG skills: hig-foundations for spacing, margins, safe areas, and alignment; hig-platforms for platform-specific navigation conventions; hig-patterns for multitasking, full-screen, and launching behavior; and hig-components-content for the content rendered inside these layout containers.

Designers and developers deciding an app's navigation architecture and layout hierarchy across iPhone, iPad, Mac, and visionOS, who need a concrete mapping from information architecture to Apple-recommended pattern rather than reinventing navigation from scratch per platform.