ios_developer

You are an iOS development expert. This skill aggregates best practices from specialized agent skills for comprehensive iOS app development.

When to Use

• Building iOS/macOS/visionOS applications
• Working with SwiftUI views and state management
• Implementing Swift Concurrency patterns
• Using Core Data for persistence
• Writing tests with Swift Testing framework
• Migrating to modern Swift patterns

Decision Tree

| Need | Reference | |------|-----------| | SwiftUI views, state, modern APIs | → swiftui.md | | What's new in SwiftUI by iOS version | → whats-new-swiftui/ | | What's new in Swift by version | → whats-new-swift/ | | async/await, actors, Sendable | → swift-concurrency.md | | Core Data persistence, threading | → core-data.md | | Swift Testing, migration from XCTest | → swift-testing.md | | General Swift patterns and practices | → swift.md |

Core Principles

1. Use Modern APIs - Prefer @Observable over ObservableObject, NavigationStack over NavigationView
2. Actor Isolation - Understand @MainActor and custom actors for thread safety
3. Structured Concurrency - Use task groups over Task.detached when possible
4. Context Safety - Never pass NSManagedObject across Core Data contexts
5. Test with Swift Testing - Prefer #expect and #require over XCTest assertions

Quick Reference

SwiftUI State Management

@Observable
@MainActor
final class ViewModel {
    var items: [Item] = []

    func load() async {
        items = await fetchItems()
    }
}

struct ContentView: View {
    @State private var viewModel = ViewModel()

    var body: some View {
        List(viewModel.items) { item in
            Text(item.name)
        }
        .task {
            await viewModel.load()
        }
    }
}

Swift Concurrency

// Structured concurrency with task group
func fetchAllData() async throws -> [Data] {
    try await withThrowingTaskGroup(of: Data.self) { group in
        for url in urls {
            group.addTask { try await fetch(url) }
        }
        return try await group.reduce(into: []) { $0.append($1) }
    }
}

// Actor for shared state
actor DataStore {
    private var cache: [String: Data] = [:]

    func get(_ key: String) -> Data? { cache[key] }
    func set(_ key: String, _ value: Data) { cache[key] = value }
}

Core Data Background Context

// Safe background processing
func importData(_ items: [ImportItem]) async throws {
    let context = container.newBackgroundContext()
    try await context.perform {
        for item in items {
            let entity = Entity(context: context)
            entity.configure(from: item)
        }
        try context.save()
    }
}

// Pass IDs, not objects
let objectID = managedObject.objectID
Task.detached {
    let context = container.newBackgroundContext()
    let object = try context.existingObject(with: objectID)
    // Work with object safely
}

Swift Testing

import Testing

@Test("User login succeeds with valid credentials")
func loginSuccess() async throws {
    let auth = AuthService()
    let user = try #require(await auth.login(email: "test@example.com", password: "valid"))
    #expect(user.isAuthenticated)
}

@Test(arguments: ["admin", "user", "guest"])
func rolePermissions(role: String) {
    let permissions = Permissions(role: role)
    #expect(permissions.canRead)
}

References

• swiftui.md - SwiftUI best practices, state management, modern APIs
• whats-new-swiftui/ - SwiftUI features by iOS version (14, 15, 16, 17, 18, 26)
• whats-new-swift/ - Swift language features by version (5.1-6.1)
• swift-concurrency.md - async/await, actors, Sendable, Swift 6 migration
• core-data.md - Core Data patterns, threading, migrations
• swift-testing.md - Swift Testing framework, XCTest migration
• swift.md - General Swift development patterns

External Resources

For more reference, use these open-source agent skills and documentation services:

AvdLee Skills

• SwiftUI-Agent-Skill - SwiftUI best practices
• Swift-Concurrency-Agent-Skill - Swift Concurrency patterns
• Core-Data-Agent-Skill - Core Data guidance
• Swift-Testing-Agent-Skill - Swift Testing framework

Dimillian Skills

• Skills Repository - iOS development skills collection
  • SwiftUI Liquid Glass - iOS 26+ Liquid Glass API
  • SwiftUI UI Patterns - View composition and state
  • SwiftUI View Refactor - Code consistency patterns
  • SwiftUI Performance Audit - Performance optimization
  • Swift Concurrency Expert - Swift 6.2+ concurrency
  • iOS Debugger Agent - Build and debug workflows
  • App Store Changelog - Release notes generation

twostraws Skills

• SwiftUI-Agent-Skill - SwiftUI best practices and patterns

Apple Documentation

• sosumi.ai - AI-readable Apple Developer documentation
  • Replace developer.apple.com with sosumi.ai in URLs (e.g., https://sosumi.ai/documentation/swiftui/view)
  • MCP server at https://sosumi.ai/mcp with tools: searchAppleDocumentation, fetchAppleDocumentation, fetchAppleVideoTranscript