THE DEVELOPER EDITION / REVIEWED 26 OCT 2026

Sources behind the visual developer guide

Platform sources reviewed October 26, 2026.

Primary sources

• Designing for iPhone Duo: displays, controls, reserved regions, and layout principles.
• Preparing your app for iPhone Duo: implementation guidance.
• Three steps to make your app shine: SDK tiers and preparation workflow.
• Xcode 27.2 RC release notes: version-specific simulator limitations.
• Screenshot specifications: submission assets and the April 2027 requirement.
• ReservedRegion, ArrangementView, and NavigationSplitView: API references.

How to read the guide

Start with the six-chapter interactive introduction. Continue to the guided lab for comparisons and signals, the audit tutorial for real source edits, or the example apps for browser demos. The shared Find control searches chapter and reference topic titles and descriptions; it is not a full-text documentation search.

The introduction saves exercise checkpoints and the last chapter in browser localStorage. A return visit offers Resume; merely visiting a chapter does not mark it complete. Its drafts and selections remain in memory and reset on reload. No analytics or demo-note content is sent to a server.

The explorer is an educational browser diagram, not an iOS simulator. Display proportions, gutter sizes, and control dimensions are illustrative. Pose choices explain behavior; they do not recommend pose-based branches or fixed hinge thresholds in app code. Split View traits must be read from the actual view. Camera and fold guides can be toggled to understand their roles.

The final chapter includes a complete downloadable SwiftUI project, compiled for a generic iOS Simulator destination using Xcode 27.1 and the iOS 27.1 SDK. Compilation is not a substitute for running the transition and accessibility checks in its README. Its SDK comparison is an illustrative browser model.

Code cards are labeled patterns or excerpts. App-specific view names and actions are placeholders. The full tutorial contains the verified edits to the bundled Notes fixture. Its audit counts are recorded example results, not an audit of the visitor's app.

Apple's documents provide the platform API guidance. Content is a reviewed snapshot dated above, not a live feed or a scheduled monitor. No third-party code or media was copied into the site.

Visual palette

Surface, text, and action colors were inspected on Apple’s iPhone Duo product page on October 28, 2026. The guide uses its white and light gray surfaces, near-black text, and blue actions, with supporting pale blue tints. Product imagery is not copied.