swift-core_skill

Overview

This skill captures Swift 6 fundamentals for all Apple platforms, focusing on concurrency, architecture, testing, internationalization, and performance. It provides practical guidance and a reproducible agent workflow to validate implementations across iOS, macOS, iPadOS, watchOS, and visionOS.

How this skill works

Before any implementation spawn three agents using TeamCreate: fuse-ai-pilot:explore-codebase, fuse-ai-pilot:research-expert, and mcp__apple-docs__search_apple_docs to analyze patterns, verify Swift 6 changes, and check concurrency guidance. Follow the recommended patterns (actors, @Observable, string catalogs) during development and run fuse-ai-pilot:sniper after implementation for automated validation and checks.

When to use it

• Implementing async/await, actors, and Sendable semantics in app code
• Designing app architecture (MVVM, Clean Architecture) across Apple platforms
• Writing and running async XCTest unit and integration tests
• Localizing UI with Xcode String Catalogs for all user-facing text
• Profiling and optimizing runtime performance using Instruments

Best practices

• Prefer actors for shared mutable state instead of locks or synchronized classes
• Adopt @Observable for view-model state to simplify reactive patterns and improve performance
• Use structured concurrency (async/await) throughout; avoid completion-handler patterns
• Localize all user-facing strings with String Catalogs; enforce during reviews
• Profile release builds (-O) with Instruments and optimize hotspots before shipping
• Favor value types (structs) over classes when appropriate to reduce reference-cycle costs

Example use cases

• Refactoring a legacy networking layer to async/await and marking types Sendable where needed
• Implementing an MVVM flow with @Observable view models and dependency injection for testability
• Converting unit tests to async XCTest without expectations and taking advantage of structured concurrency
• Replacing NSLocalizedString usage with Xcode String Catalogs and verifying translations
• Profiling a slow view on a device with Instruments and applying lazy loading to eliminate main-thread work