focus-engine

This skill is a reference and implementation guide for focus behavior in SwiftUI and UIKit apps across Apple platforms (iOS 26+, iPadOS, macOS, tvOS, and visionOS connected-input paths). It addresses the tricky, platform-specific work of managing keyboard, directional, remote, game-controller, and scene-level focus, including @FocusState, defaultFocus, focused values, focusable interactions, focus sections, focus restoration after presentation changes, and custom routing with UIFocusGuide. It also draws an explicit boundary: gaze-driven hover on visionOS is treated as an input affordance rather than focus, and VoiceOver/Switch Control accessibility focus is handed off to a separate accessibility skill.

The skill supplies concrete SwiftUI and UIKit patterns, such as using an optional Hashable enum with @FocusState to move focus between fields, exposing focused scene values to command menus and toolbars, and building focusable custom controls that prefer semantic controls like Button before adding .focusable. It documents platform availability details (for example focusSection on macOS 13+ and tvOS 15+) and includes reference files for focus patterns, multi-platform focus, and debugging focus (including UIFocusDebugger), plus an evals file for validating the guidance.

It is aimed at Swift/iOS developers building multi-platform apps that must handle keyboard, remote, and directional navigation correctly, especially for tvOS geometric focus, watchOS Digital Crown input, and macOS Full Keyboard Access. It is documentation and code guidance with no execution or system side effects.