Network Framework Migration Guides

Do I Need to Migrate?

What networking API are you using?

├─ URLSession for HTTP/HTTPS REST APIs?
│   └─ Stay with URLSession — it's the RIGHT tool for HTTP
│      URLSession handles caching, cookies, auth challenges,
│      HTTP/2/3, and is heavily optimized for web APIs.
│      Network.framework is for custom protocols, NOT HTTP.
│
├─ BSD Sockets (socket, connect, send, recv)?
│   └─ Migrate to NWConnection (iOS 12+)
│      → See Migration 1 below
│
├─ NWConnection / NWListener?
│   ├─ Need async/await? → Migrate to NetworkConnection (iOS 26+)
│   │   → See Migration 2 below
│   └─ Callback-based code working fine? → Stay (not deprecated)
│
├─ URLSession StreamTask for TCP/TLS?
│   └─ Need UDP or custom protocols? → NetworkConnection
│      Need just TCP/TLS for HTTP? → Stay with URLSession
│      → See Migration 3 below
│
├─ SCNetworkReachability?
│   └─ DEPRECATED — Replace with NWPathMonitor (iOS 12+)
│      let monitor = NWPathMonitor()
│      monitor.pathUpdateHandler = { path in
│          print(path.status == .satisfied ? "Online" : "Offline")
│      }
│
└─ CFSocket / NSStream?
    └─ DEPRECATED — Replace with NWConnection (iOS 12+)
       → See Migration 1 below

Migration 1: From BSD Sockets to NWConnection

Migration mapping

Example migration

Before (BSD Sockets)

// BEFORE — Blocking, manual DNS, error-prone
var hints = addrinfo()
hints.ai_family = AF_INET
hints.ai_socktype = SOCK_STREAM

var results: UnsafeMutablePointer<addrinfo>?
getaddrinfo("example.com", "443", &hints, &results)

let sock = socket(results.pointee.ai_family, results.pointee.ai_socktype, 0)
connect(sock, results.pointee.ai_addr, results.pointee.ai_addrlen) // BLOCKS

let data = "Hello".data(using: .utf8)!
data.withUnsafeBytes { ptr in
    send(sock, ptr.baseAddress, data.count, 0)
}

After (NWConnection)

// AFTER — Non-blocking, automatic DNS, type-safe
let connection = NWConnection(
    host: NWEndpoint.Host("example.com"),
    port: NWEndpoint.Port(integerLiteral: 443),
    using: .tls
)

connection.stateUpdateHandler = { state in
    if case .ready = state {
        let data = Data("Hello".utf8)
        connection.send(content: data, completion: .contentProcessed { error in
            if let error = error {
                print("Send failed: \(error)")
            }
        })
    }
}

connection.start(queue: .main)

Benefits

• 20 lines → 10 lines
• No manual DNS, no blocking, no unsafe pointers
• Automatic Happy Eyeballs, proxy support, WiFi Assist

Migration 2: From NWConnection to NetworkConnection (iOS 26+)

Why migrate

• Async/await eliminates callback hell
• TLV framing and Coder protocol built-in
• No [weak self] needed (async/await handles cancellation)
• State monitoring via async sequences

Migration mapping

Example migration

Before (NWConnection)

// BEFORE — Completion handlers, manual memory management
let connection = NWConnection(host: "example.com", port: 443, using: .tls)

connection.stateUpdateHandler = { [weak self] state in
    switch state {
    case .ready:
        self?.sendData()
    case .waiting(let error):
        print("Waiting: \(error)")
    case .failed(let error):
        print("Failed: \(error)")
    default:
        break
    }
}

connection.start(queue: .main)

func sendData() {
    let data = Data("Hello".utf8)
    connection.send(content: data, completion: .contentProcessed { [weak self] error in
        if let error = error {
            print("Send error: \(error)")
            return
        }
        self?.receiveData()
    })
}

func receiveData() {
    connection.receive(minimumIncompleteLength: 10, maximumLength: 10) { [weak self] (data, context, isComplete, error) in
        if let error = error {
            print("Receive error: \(error)")
            return
        }
        if let data = data {
            print("Received: \(data)")
        }
    }
}

After (NetworkConnection)

// AFTER — Async/await, automatic memory management
let connection = NetworkConnection(
    to: .hostPort(host: "example.com", port: 443)
) {
    TLS()
}

// Monitor states in background task