swift-ios

Hand-off — the language vs the platform. This skill owns the platform: SwiftUI/UIKit views, app lifecycle, Xcode, iOS APIs, App Store shipping. Language-level Swift — Swift 6 data-race safety and approachable concurrency, actors and task groups, some vs any, ARC and performance, Swift Testing, macros — is this skill's own ground. A concurrency error, a hang, a data race or a retain cycle belongs here. Interface feel, springs and materials: ../motion-craft/SKILL.md.

Native Apple-platform apps: the code is .swift, the UI is SwiftUI, and the compiler enforces actor isolation. If the answer is a @MainActor, @Observable, async let, #expect, NavigationStack, or @Model, you are in the right place.

First move: match the project before you write a line

Mismatched language modes produce diagnostics you cannot reproduce and "fixes" that break the user's build. Pin the ground truth first.