moai-lang-swift

Metadata

| Field | Value | | ----- | ----- | | Skill Name | moai-lang-swift | | Version | 4.0.0 (2025-11-12) | | Allowed tools | Read, Bash, Context7 MCP | | Auto-load | On demand when keywords detected | | Tier | Language Enterprise | | Context7 Integration | ✅ Swift/SwiftUI/Vapor/Combine |

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What It Does

Swift 6.0 enterprise development featuring modern concurrency with async/await, SwiftUI for declarative UI, Combine for reactive programming, server-side Swift with Vapor, and enterprise-grade patterns for scalable, performant applications. Context7 MCP integration provides real-time access to official Swift and ecosystem documentation.

Key capabilities:

• ✅ Swift 6.0 with strict concurrency and actor isolation
• ✅ Advanced async/await patterns and structured concurrency
• ✅ SwiftUI 6.0 for declarative UI development
• ✅ Combine framework for reactive programming
• ✅ Server-side Swift with Vapor 4.x
• ✅ Enterprise architecture patterns (MVVM, TCA, Clean Architecture)
• ✅ Context7 MCP integration for real-time docs
• ✅ Performance optimization and memory management
• ✅ Testing strategies with XCTest and Swift Testing
• ✅ Swift Concurrency with actors and distributed actors

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When to Use

Automatic triggers:

• Swift 6.0 development discussions
• SwiftUI and iOS/macOS app development
• Async/await and concurrency patterns
• Combine reactive programming
• Server-side Swift and Vapor development
• Enterprise mobile application architecture

Manual invocation:

• Design iOS/macOS application architecture
• Implement async/await patterns
• Optimize performance and memory usage
• Review enterprise Swift code
• Implement reactive UI with Combine
• Troubleshoot concurrency issues

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Technology Stack (2025-11-12)

| Component | Version | Purpose | Status | |-----------|---------|---------|--------| | Swift | 6.0.1 | Core language | ✅ Current | | SwiftUI | 6.0 | Declarative UI | ✅ Current | | Combine | 6.0 | Reactive programming | ✅ Current | | Vapor | 4.102.0 | Server-side framework | ✅ Current | | Xcode | 16.2 | Development environment | ✅ Current | | Swift Concurrency | 6.0 | Async/await & actors | ✅ Current | | Swift Testing | 0.10.0 | Modern testing framework | ✅ Current |

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Quick Start: Hello Async/Await

import Foundation

// Swift 6.0 with async/await
actor GreeterService {
    func greet(name: String) -> String {
        "Hello, \(name)!"
    }
}

// Usage
Task {
    let service = GreeterService()
    let greeting = await service.greet(name: "Swift")
    print(greeting)
}

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Level 1: Quick Reference

Core Concepts

1. Async/Await - Modern concurrency without callbacks

   • Function marked with async - Suspends for I/O
   • Caller uses await - Waits for result
   • Native error handling with throws
   • Replaces callbacks and completion handlers

2. SwiftUI - Declarative UI framework

   • State-driven views update automatically
   • @State for local state
   • @StateObject for ViewModels
   • Composable views with modifiers

3. Combine - Reactive programming

   • Publishers emit values
   • Operators transform pipelines
   • Subscribers receive results
   • Error handling with .catch

4. Actors - Thread-safe state isolation

   • Protect mutable state automatically
   • Replace locks and semaphores
   • @MainActor for UI thread
   • Distributed actors for RPC

5. Vapor - Server-side Swift

   • Async route handlers
   • Database integration (Fluent)
   • Middleware for cross-cutting concerns
   • Type-safe API responses

Project Structure

MyApp/
├── Sources/
│   ├── App.swift                 # Entry point
│   ├── Models/                   # Data types
│   ├── Services/                 # Business logic
│   ├── ViewModels/               # UI state management
│   └── Views/                    # SwiftUI components
├── Tests/
│   ├── UnitTests/
│   └── IntegrationTests/
└── Package.swift                 # Dependencies

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Level 2: Implementation Patterns

Async/Await Pattern

import Foundation

// Structured async function
func fetchData() async throws -> String {
    let url = URL(string: "https://api.example.com/data")!
    let (data, _) = try await URLSession.shared.data(from: url)
    return String(data: data, encoding: .utf8) ?? ""
}

// Concurrent operations with TaskGroup
func loadMultipleResources() async throws -> (String, String) {
    try await withThrowingTaskGroup(of: (String, String).self) { group in
        group.addTask { ("users", try await fetchUsers()) }
        group.addTask { ("posts", try await fetchPosts()) }

        var results: [String: String] = [:]
        for try await (key, value) in group {
            results[key] = value
        }
        return (results["users"] ?? "", results["posts"] ?? "")
    }
}

SwiftUI State Management

import SwiftUI

@MainActor
class ContentViewModel: ObservableObject {
    @Published var items: [String] = []
    @Published var isLoading = false

    func loadItems() async {
        isLoading = true
        defer { isLoading = false }

        do {
            items = try await fetchItems()
        } catch {
            items = []
        }
    }
}

struct ContentView: View {
    @StateObject private var viewModel = ContentViewModel()

    var body: some View {
        NavigationView {
            VStack {
                if viewModel.isLoading {
                    ProgressView()
                } else {
                    List(viewModel.items, id: \.self) { item in
                        Text(item)
                    }
                }
            }
            .navigationTitle("Items")
            .task {
                await viewModel.loadItems()
            }
        }
    }
}

Actor Isolation Pattern

// Thread-safe counter
actor CounterService {
    private var count: Int = 0

    func increment() { count += 1 }
    func decrement() { count -= 1 }
    func getCount() -> Int { count }
}

// Usage (automatically thread-safe)
Task {
    let counter = CounterService()
    await counter.increment()
    let value = await counter.getCount()
}

Vapor Server Route

import Vapor

func routes(_ app: Application) throws {
    // GET /api/users
    app.get("api", "users") { req async -> [String: String] in
        return ["status": "success"]
    }

    // POST /api/users
    app.post("api", "users") { req async -> HTTPStatus in
        // Save user
        return .created
    }
}

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Level 3: Advanced Topics

Concurrency Best Practices

1. Prefer async/await over Combine for sequential operations
2. Use actors for mutable shared state (not locks)
3. Mark UI code @MainActor to ensure main thread
4. Handle cancellation properly in long-running tasks
5. Avoid blocking operations (no sleep, no synchronous I/O)

Performance Optimization

• Memory: Use value types (struct) by default
• CPU: Profile with Xcode Instruments
• Rendering: Keep SwiftUI view body pure
• Networking: Implement request caching
• Database: Use connection pooling in Vapor

Security Patterns

• Input validation: Always validate user input
• Error handling: Don't expose internal errors to users
• Encryption: Use CryptoKit for sensitive data
• Authentication: Implement JWT or OAuth2
• SQL injection prevention: Use parameterized queries

Testing Strategy

• Unit tests: Pure functions with XCTest
• Integration tests: Database and API tests
• UI tests: SwiftUI view behavior
• Mocking: Use protocols for dependency injection

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Context7 MCP Integration

Get latest Swift documentation on-demand:

# Access Swift documentation via Context7
from context7 import resolve_library_id, get_library_docs

# Swift Language Documentation
swift_id = resolve_library_id("swift")
docs = get_library_docs(
    context7_compatible_library_id=swift_id,
    topic="structured-concurrency",
    tokens=5000
)

# SwiftUI Documentation
swiftui_id = resolve_library_id("swiftui")
swiftui_docs = get_library_docs(
    context7_compatible_library_id=swiftui_id,
    topic="state-management",
    tokens=4000
)

# Vapor Framework Documentation
vapor_id = resolve_library_id("vapor")
vapor_docs = get_library_docs(
    context7_compatible_library_id=vapor_id,
    topic="routing",
    tokens=3000
)

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Related Skills & Resources

Language Integration:

• Skill("moai-context7-lang-integration"): Latest Swift/Vapor documentation

Quality & Testing:

• Skill("moai-foundation-testing"): Swift testing best practices
• Skill("moai-foundation-trust"): TRUST 5 principles application

Security & Performance:

• Skill("moai-foundation-security"): Security patterns for Swift
• Skill("moai-essentials-debug"): Swift debugging techniques

Official Resources:

• Swift.org Documentation
• Apple Developer
• SwiftUI Tutorials
• Vapor Documentation
• Swift Forums

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Troubleshooting

Problem: Sendable conformance error Solution: Implement Sendable protocol or use @Sendable closure

Problem: Actor isolation violation Solution: Use nonisolated for safe properties or proper await calls

Problem: Memory leaks in closures Solution: Capture [weak self] to break retain cycles

Problem: SwiftUI view not updating Solution: Ensure state changes happen on @MainActor

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Changelog

• ** .0** (2025-11-12): Enterprise upgrade - Progressive Disclosure structure, 90% content reduction, Context7 integration
• v3.0.0 (2025-03-15): SwiftUI 5.0 and Combine 6.0 patterns
• v2.0.0 (2025-01-10): Basic Swift 5.x patterns
• v1.0.0 (2024-12-01): Initial release

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Resources

For working examples: See examples.md

For API reference: See reference.md

For advanced patterns: See full SKILL.md in documentation archive

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Last updated: 2025-11-12 | Maintained by moai-adk team