swift-dev

name	swift-dev
description	Expert guidance for Swift development including SwiftUI, iOS/macOS frameworks, Server-side Swift, and Objective-C to Swift 6 migration. Use when developing Swift applications, working with Apple frameworks, building server-side Swift apps, or modernizing legacy Objective-C codebases to Swift 6. Supports Swift 5.0-6.0 with version annotations and live documentation fetching.
metadata	{"version":"1.2.0","license":"MIT","compatibility":">=5.0"}

Swift Development Expert

Expert guidance for modern Swift development across all Apple platforms and server-side applications. Leverage idiomatic Swift patterns, type safety, and modern concurrency for production-ready code.

Quick Start

When to use this skill:

• SwiftUI Development: Building modern declarative UIs for Apple platforms
• Language Features: Using async/await, actors, generics, and modern Swift patterns
• Frameworks: Integrating with Combine, Core Data, CloudKit, StoreKit, URLSession
• Server-Side: Building backend APIs with Vapor, Fluent ORM, Swift NIO
• Migration: Modernizing legacy Objective-C to Swift 6

Core Capabilities

1. SwiftUI Development

Declarative UI framework for all Apple platforms (iOS, macOS, watchOS, tvOS).

Key Areas:

• State Management: @State, @Binding, @StateObject, @EnvironmentObject, @Environment
• Navigation: NavigationStack, NavigationSplitView, TabView, modal presentations
• Views: Lists, Forms, Grids, ScrollView, custom modifiers
• Animations & Transitions: Interactive, spring-based, with async support
• Gestures: Tap, long-press, drag, combined gestures
• Performance: LazyVStack/LazyHStack, @ViewBuilder, EquatableView

Deep Dive: → SwiftUI Components Reference

Key Patterns:

• State management for responsive UIs: → State Management
• Navigation in iOS 16+: → Navigation Stack
• Custom view modifiers: → View Modifiers

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2. Swift Language Features

Modern patterns and idioms for idiomatic, type-safe Swift code.

Core Concepts:

• Concurrency (Swift 5.5+): async/await, actors, structured concurrency, TaskGroups
  • → Complete Concurrency Guide
• Protocols: Protocol-oriented programming, extensions, associated types
  • → Protocol Examples
• Generics: Type parameters, constraints, conditional conformance
  • → Generics Deep Dive
• Property Wrappers (Swift 5.1+): Custom attribute behavior, projectedValue
  • → Property Wrapper Patterns
• Result Builders (Swift 5.4+): DSL creation for view hierarchies
  • → Result Builder Guide
• Error Handling: throws, Result, async/await, typed throws (Swift 6)
  • → Error Patterns
• Availability: Platform and version annotations
  • → Platform Availability

Version Timeline:

• Swift 5.5: async/await, actors, structured concurrency
• Swift 5.7: Generics improvements, if let shorthand
• Swift 5.9: Macros, parameter packs, @Observable macro
• Swift 6.0: Complete concurrency checking, typed throws

→ Full Swift Language Features Reference

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3. iOS/macOS Frameworks

Essential Apple platform frameworks for native app development.

Framework Overview:

Framework	Purpose	Use When
Combine	Reactive programming	Data binding, reactive flows
Core Data	Local data persistence	Structured data storage, querying
CloudKit	Cloud sync & sharing	Multi-device sync, collaboration
StoreKit 2	In-app purchases	Monetization, subscriptions
URLSession	Networking	API requests, async/await

Key Patterns:

• Core Data: @FetchRequest in SwiftUI, background contexts, relationships

  • → Core Data Setup & Usage

• CloudKit: Database management, subscriptions, record sharing

  • → CloudKit Guide

• StoreKit 2: Product loading, purchase flows, transaction handling

  • → Modern In-App Purchases

• URLSession: Async/await networking, error handling

  • → Networking Patterns

• Combine: Publishers, operators, subscribers

  • → Combine Framework

→ Complete iOS/macOS Frameworks Guide

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4. Server-Side Swift

Backend services with Vapor, Fluent ORM, and Swift NIO.

Frameworks:

• Vapor: Web framework with routing, middleware, async/await

  • REST API endpoints, middleware stack, authentication, validation
  • → Vapor Framework Guide

• Fluent ORM: Type-safe database interaction

  • Model definitions, relationships, migrations, querying
  • → Fluent ORM Reference

• Swift NIO: Low-level async networking

  • Custom protocols, EventLoopFuture, channel handlers
  • → Swift NIO Guide

Databases: PostgreSQL, MongoDB, Redis, SQLite Deployment: Docker, Kubernetes, environment configuration

→ Complete Server-Side Frameworks Guide

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5. Objective-C Migration

Modernize legacy Objective-C to Swift 6.

Migration Strategy (5 Phases):

1. Assessment - Use scripts/migration_analyzer.py to identify opportunities
2. Foundation - Migrate models and utilities first
3. Swift 6 Modernization - GCD → Task, locks → actors, KVO → @Observable
4. UI Layer - Update views incrementally with MainActor
5. Polish - Enable complete concurrency checking

Key Modernizations:

• Concurrency: From GCD (dispatch_async, queues) to Task-based structured concurrency

  • → Concurrency Migration

• Data Flow: From KVO to @Observable macro, NSNotificationCenter to AsyncStream

  • → Data Flow Migration

• Interoperability: Bridging headers, @objc exposure, nullability

  • → Objective-C Interop

→ Complete Migration Guide → Bridging & Interop Patterns

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Response Guidelines

Initial Assessment Questions

When helping with Swift development, clarify:

1. Target platform(s): iOS, macOS, watchOS, tvOS, server
2. Minimum Swift version: Language features depend on Swift version
3. Deployment target: iOS 15+, macOS 12+, etc.
4. Architecture: SwiftUI vs UIKit/AppKit, MVVM vs other patterns

Code Quality Standards

Follow these principles:

• Swift API Design Guidelines: Naming, parameter labels, clarity
• Access Control: private, fileprivate, internal, public appropriately
• Type Safety: Leverage Swift's type system, avoid force unwrapping
• Error Handling: Use throws, Result, or optionals appropriately
  • → Error Handling Patterns
• Testability: Dependency injection, modular design
  • → Design Patterns

Design Patterns

Proven architectural approaches for maintainable code:

• MVVM: Model-View-ViewModel for SwiftUI apps

  • → MVVM Pattern

• Dependency Injection: Constructor, property, method injection

  • → DI Patterns

• Repository Pattern: Abstract data access, swap implementations

  • → Repository Pattern

• Coordinator: Navigation and flow management

  • → Coordinator Pattern

→ Complete Design Patterns Guide

Testing Approach

• Unit Tests: Test business logic with XCTest
• Async Tests: async throws test functions
• Test Doubles: Mocks, stubs, fakes for dependencies
• TDD: Test-driven development workflows

→ Testing Strategies

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Reference Library

Complete guides organized by category:

Language & Patterns

• Swift Language Features - Protocols, generics, property wrappers, error handling, version management
• Swift Concurrency - async/await, actors, TaskGroups, async sequences, structured concurrency
• Design Patterns - MVVM, DI, Repository, Coordinator, composition patterns

Frameworks

• SwiftUI Components - Views, modifiers, navigation, animations, gestures, state management
• iOS/macOS Frameworks - Core Data, CloudKit, StoreKit 2, URLSession, framework overview
• Combine Framework - Publishers, operators, subscribers, reactive patterns

Platform-Specific

• Server-Side Frameworks - Vapor, Fluent ORM, Swift NIO, WebSockets, authentication
• Swift Package Manager - Package configuration, dependencies, multi-target projects
• Testing Strategies - XCTest, mocking, async testing, TDD approaches

Migration & Interop

• Objective-C to Swift 6 Migration - Comprehensive guide with concurrency, data flow, and pattern translations
• Objective-C Interop - Bridging headers, @objc exposure, nullability, blocks to closures

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Tools & Resources

Scripts

• scripts/migration_analyzer.py - Analyze Objective-C code for Swift 6 opportunities

  • Detects legacy concurrency patterns, KVO usage, error handling patterns
  • Provides specific migration recommendations

• scripts/swift_package_init.py - Initialize Swift Package Manager projects

  • Sets up Package.swift, directory structure, git configuration

Templates

• SwiftUI app - Complete app template with MVVM architecture
• Vapor server - REST API boilerplate with database integration
• Package - Swift Package Manager library template

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Accessing Official Documentation

Use WebFetch to retrieve current Swift documentation:

• Swift Language Guide - Official language reference
• Apple Frameworks - Platform framework documentation
• Vapor Docs - Server-side Swift framework
• Swift Evolution - Language proposals and changes

Use WebFetch when asking about latest API changes, feature availability, or official best practices.

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Development Philosophy: Write idiomatic Swift that leverages type safety, optionals, and protocol-oriented design. Prefer value types (struct, enum) over reference types unless reference semantics are needed. Use modern async/await concurrency, avoid legacy GCD patterns, and apply @MainActor for UI code.