Network.framework Reference

Complete API reference for Network.framework. Covers NWConnection (iOS 12-25), NetworkConnection (iOS 26+) with structured concurrency, TLV framing, Coder protocol, and migration patterns.

When to Use This Reference

Use this reference when you need:

• NWConnection state machine and patterns
• NetworkConnection async/await APIs (iOS 26+)
• TLV (Type-Length-Value) message framing
• Coder protocol for Codable send/receive
• NetworkListener and NetworkBrowser patterns
• Migration from BSD sockets or URLSession

For troubleshooting: See networking-diag for connection issues.

Example Prompts

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

• "How do I create a TLS connection with NWConnection?"
• "How do I use NetworkConnection with async/await in iOS 26?"
• "How do I implement TLV framing for message boundaries?"
• "How do I use Coder protocol to send Codable objects?"
• "When should I use Network.framework vs URLSession?"
• "How do I set up a NetworkListener for incoming connections?"

What's Covered

NWConnection (iOS 12-25)

• Connection creation with endpoints
• State machine and stateUpdateHandler
• Completion-based send/receive
• TLS configuration
• UDP batching

NetworkConnection (iOS 26+)

• Declarative protocol stacks
• async/await send/receive
• TLV built-in framing
• Coder protocol for Codable
• State property observation

Server Patterns

• NWListener (iOS 12-25)
• NetworkListener (iOS 26+)
• Service discovery with Browser
• Wi-Fi Aware peer-to-peer

Advanced Features

• Smart connection establishment (Happy Eyeballs)
• Multipath TCP
• TCP Fast Open
• User-space networking

Key Pattern

iOS 26+ NetworkConnection

// TLS connection with Coder
let connection = NetworkConnection(
    to: .hostPort(host: "www.example.com", port: 1029)
) {
    Coder(GameMessage.self, using: .json) {
        TLS()
    }
}

// Send Codable directly
try await connection.send(GameMessage(type: .move, data: moveData))

// Receive Codable
for try await (message, _) in connection.messages {
    handleMessage(message)
}

iOS 12-25 NWConnection

let connection = NWConnection(
    to: .hostPort(host: "www.example.com", port: 1029),
    using: .tls
)
connection.stateUpdateHandler = { state in
    switch state {
    case .ready: // Connected
    case .failed(let error): // Handle failure
    default: break
    }
}
connection.start(queue: .main)

Documentation Scope

This page documents the axiom-network-framework-ref reference skill—complete API coverage Claude uses when you need specific Network.framework APIs or implementation patterns.

For troubleshooting: See networking-diag for connection failures.

For architecture: See networking for when to use Network.framework vs URLSession.

Related

• networking — Network architecture decisions
• networking-diag — Connection troubleshooting
• networking-auditor — Deprecated API scanning

Resources

WWDC: 2018-715 (NWConnection), 2025-250 (NetworkConnection)

Docs: /network, /network/nwconnection