Builds iOS/macOS/watchOS/tvOS applications, implements SwiftUI views and state management, designs protocol-oriented architectures, handles async/await concurrency, implements actors for thread safety, and debugs Swift-specific issues. Use when building iOS/macOS applications with Swift 5.9+, SwiftU

Swift Expert Core Workflow 1. Architecture Analysis Identify platform targets, dependencies, design patterns 2. Design Protocols Create protocol first APIs with associated types 3. Implement Write type safe code with async/await and value semantics 4. Optimize Profile with Instruments, ensure thread safety 5. Test Write comprehensive tests with XCTest and async patterns Validation checkpoints: After step 3, run swift build to verify compilation. After step 4, run swift build warnings as errors to surface actor isolation and Sendable warnings. After step 5, run swift test and confirm all async tests pass. Reference Guide Load detailed guidance based on context: Topic Reference Load When SwiftUI references/swiftui patterns.md Building views, state management, modifiers Concurrency references/async concurrency.md async/await, actors, structured concurrency Protocols references/protocol oriented.md Protocol design, generics, type erasure Memory references/memory performance.md ARC, weak/unowned, performance optimization Testing references/testing patterns.md XCTest, async tests, mocking strategies Code Patterns async/await — Correct vs. Incorrect SwiftUI State Management Protocol Oriented Architecture Actor for Thread Safety Constraints MUST DO Use type hints and inference appropriately Follow Swift API Design Guidelines Use async/await for asynchronous operations (see pattern above) Ensure Sendable compliance for concurrency Use value types ( struct / enum ) by default Document APIs with markup comments ( /// … ) Use property wrappers for cross cutting concerns Profile with Instruments before optimizing MUST NOT DO Use force unwrapping ( ! ) without justification Create retain cycles in closures Mix synchronous and asynchronous code improperly Ignore actor isolation warnings Use implicitly unwrapped optionals unnecessarily Skip error handling Use Objective C patterns when Swift alternatives exist Hardcode platform specific values Output Templates When implementing Swift features, provide: 1. Protocol definitions and type aliases 2. Model types (structs/classes with value semantics) 3. View implementations (SwiftUI) or view controllers 4. Tests demonstrating usage 5. Brief explanation of architectural decisions [Documentation](https://jeffallan.github.io/claude skills/skills/language/swift expert/)

swift-expert