networking-layer

Generate a modern, protocol-based networking layer using Swift's async/await concurrency, with proper error handling and easy testability.

When This Skill Activates

Use this skill when the user:

• Asks to "add networking" or "create API client"
• Mentions "HTTP layer" or "REST API"
• Wants to "fetch data from API"
• Asks about "URLSession wrapper" or "network requests"

Pre-Generation Checks

1. Project Context Detection

• [ ] Check Swift version (async/await requires Swift 5.5+)
• [ ] Check deployment target (async/await requires iOS 15+ / macOS 12+)
• [ ] Search for existing networking implementations
• [ ] Identify source file locations

2. Conflict Detection

Search for existing networking:

Glob: **/*API*.swift, **/*Network*.swift, **/*Client*.swift
Grep: "URLSession" or "HTTPURLResponse"

If found, ask user:

• Replace existing implementation?
• Extend with new endpoints?

Configuration Questions

Ask user via AskUserQuestion:

1. Authentication type?

   • Bearer token
   • API key (header or query param)
   • None
   • Custom

2. Base URL configuration?

   • Single environment
   • Multiple environments (dev/staging/prod)

3. Additional features?

   • Retry logic with exponential backoff
   • Request/response logging
   • Caching

Generation Process

Step 1: Create Core Files

Generate these files:

1. APIClient.swift - Protocol and implementation
2. APIEndpoint.swift - Endpoint definition protocol
3. NetworkError.swift - Typed errors
4. APIConfiguration.swift - Base URL and auth config

Step 2: Optional Files

Based on configuration:

• RetryPolicy.swift - If retry logic selected
• NetworkLogger.swift - If logging selected

Step 3: Determine File Location

Check project structure:

• If Sources/ exists → Sources/Networking/
• If App/ exists → App/Networking/
• Otherwise → Networking/

Swift 6.2 Concurrency Notes

Reference: Apple's Swift Concurrency Updates

@concurrent for Background Work

Use @concurrent to offload heavy processing:

@concurrent
static func parseResponse<T: Decodable>(_ data: Data) async throws -> T {
    try JSONDecoder().decode(T.self, from: data)
}

MainActor for UI Updates

Keep UI-related code on MainActor:

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

    func fetch() async {
        items = try await apiClient.fetch(ItemsEndpoint())
    }
}

Output Format

After generation, provide:

Files Created

Sources/Networking/
├── APIClient.swift           # Protocol + URLSession implementation
├── APIEndpoint.swift         # Endpoint protocol
├── NetworkError.swift        # Error types
├── APIConfiguration.swift    # Config (base URL, auth)
└── Endpoints/                # Example endpoints
    └── ExampleEndpoint.swift

Integration Steps

Define an Endpoint:

struct UsersEndpoint: APIEndpoint {
    typealias Response = [User]

    var path: String { "/users" }
    var method: HTTPMethod { .get }
}

Make a Request:

let client = URLSessionAPIClient(configuration: .production)
let users = try await client.request(UsersEndpoint())

With SwiftUI:

struct UsersView: View {
    @State private var users: [User] = []
    @Environment(\.apiClient) private var apiClient

    var body: some View {
        List(users) { user in
            Text(user.name)
        }
        .task {
            users = try await apiClient.request(UsersEndpoint())
        }
    }
}

Testing

Use MockAPIClient for tests:

let mockClient = MockAPIClient()
mockClient.mockResponse(for: UsersEndpoint.self, response: [User.mock])

let viewModel = UsersViewModel(apiClient: mockClient)
await viewModel.fetch()

XCTAssertEqual(viewModel.users.count, 1)

References

• networking-patterns.md - Architecture patterns and best practices
• templates/ - All template files
• Apple Docs: Swift Concurrency Updates (Swift 6.2)