This skill should be used when the user asks to "create a SwiftUI view", "build an iOS app", "set up an Xcode project", "review Apple platform code", "add a widget", "create a watchOS app", "build for visionOS", "fix SwiftUI layout", or when generating any Swift code targeting Apple platforms (iOS, iPadOS, macOS, tvOS, watchOS, visionOS). Provides modern SwiftUI-first best practices covering UI patterns, app lifecycle, navigation, project structure, and platform-specific guidance. Covers Apple platform frameworks and app structure, not the language itself — for Swift language fundamentals use `swift-development` alongside it. Always generates Swift unless the project explicitly requires Objective-C.