Networking

Network.framework patterns for UDP/TCP connections. Covers NWConnection (iOS 12-25) and NetworkConnection (iOS 26+) with structured concurrency.

When to Use This Skill

Use this skill when you're:

• Implementing UDP or TCP connections
• Migrating from deprecated APIs (SCNetworkReachability, CFSocket, NSStream)
• Adding TLS/SSL to connections
• Implementing service discovery with NWBrowser
• Creating server listeners with NWListener
• Adopting async/await patterns for networking (iOS 26+)

Note: For HTTP/REST APIs, use URLSession instead. This skill is for low-level socket connections.

Example Prompts

Questions you can ask Claude that will draw from this skill:

• "How do I create a TCP connection with Network.framework?"
• "What's the modern replacement for SCNetworkReachability?"
• "How do I implement UDP with batching for better performance?"
• "I need to add TLS to my connection. How do I configure it?"
• "How do I use the new NetworkConnection API in iOS 26?"
• "My connection keeps failing on network transitions. How do I handle this?"
• "How do I implement a server listener for incoming connections?"

What's Covered

Anti-Patterns Prevented

• SCNetworkReachability (race conditions, deprecated)
• CFSocket, NSStream, CFStream (replaced by NWConnection)
• NSNetService (replaced by NWBrowser)
• Reachability checks before connecting
• Hardcoded IP addresses
• Blocking socket operations on main thread

NWConnection (iOS 12-25)

• TCP and UDP connections
• TLS with stateUpdateHandler
• UDP batch sending (30% CPU reduction)
• Network transition handling

NetworkConnection (iOS 26+)

• Async/await patterns
• Declarative TLS stacks
• UDP datagrams with batching
• TLV framing for message boundaries
• Coder protocol for Codable objects

Listening & Discovery

• NWListener for incoming connections
• NWBrowser for service discovery
• Bonjour integration

Key Pattern

Modern TCP Connection (iOS 26+)

// iOS 26+: Async/await with NetworkConnection
let connection = NetworkConnection(
    to: .hostPort(host: "example.com", port: 443),
    using: .tls
)

for try await event in connection.events {
    switch event {
    case .connected:
        try await connection.send(data)
    case .received(let data):
        process(data)
    case .closed:
        break
    }
}

Legacy TCP Connection (iOS 12-25)

// iOS 12-25: Completion-based with NWConnection
let connection = NWConnection(
    host: "example.com",
    port: 443,
    using: .tls
)

connection.stateUpdateHandler = { state in
    switch state {
    case .ready:
        self.send(data)
    case .failed(let error):
        self.handleError(error)
    default:
        break
    }
}

connection.start(queue: .main)

Documentation Scope

This page documents the axiom-networking skill—Network.framework patterns Claude uses when helping you implement UDP/TCP connections. The skill contains complete connection patterns, TLS configuration, and migration guides from deprecated APIs.

For diagnostics: See networking-diag for troubleshooting connection failures.

For API reference: See network-framework-ref for comprehensive API coverage.

Related

• networking-diag — Connection failure diagnosis and debugging
• network-framework-ref — Complete API reference
• networking-auditor — Autonomous agent scanning for deprecated APIs
• swift-concurrency — Async/await patterns for iOS 26+

Resources

WWDC: 2018-715, 2025-250

Docs: /network, /network/nwconnection