/swift-networking

Getting Started with Network.framework

API Selection

Basic TLS Connection (iOS 12+)

import Network

let connection = NWConnection(
    host: NWEndpoint.Host("api.example.com"),
    port: NWEndpoint.Port(integerLiteral: 443),
    using: .tls
)

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

connection.start(queue: .main)

Critical: Always use [weak self] in NWConnection handlers.

Basic TLS Connection (iOS 26+)

let connection = NetworkConnection(
    to: .hostPort(host: "api.example.com", port: 443)
) {
    TLS()  // TCP and IP inferred
}

func communicate() async throws {
    try await connection.send(Data("Hello".utf8))
    let response = try await connection.receive(exactly: 100).content
}

UDP Connection

// iOS 12+
let udp = NWConnection(host: "game.example.com", port: 9000, using: .udp)

// iOS 26+
let udp = NetworkConnection(to: .hostPort(host: "game.example.com", port: 9000)) { UDP() }

Custom Parameters

let parameters = NWParameters.tls
parameters.prohibitConstrainedPaths = true  // Respect Low Data Mode
parameters.prohibitExpensivePaths = true    // Don't use cellular

Send with Pacing

connection.send(content: data, completion: .contentProcessed { [weak self] error in
    // contentProcessed = network consumed data, NOW send next chunk
    self?.sendNextChunk()
})

Receive Data

connection.receive(minimumIncompleteLength: 1, maximumLength: 65536) {
    [weak self] data, context, isComplete, error in
    if let data = data {
        self?.processData(data)
        self?.receiveMore()
    }
}

UDP Batching (30% CPU Reduction)

connection.batch {
    for frame in frames {
        connection.send(content: frame, completion: .contentProcessed { _ in })
    }
}  // 100 datagrams = ~1 syscall

Debugging

Add to Xcode scheme arguments:

-NWLoggingEnabled 1
-NWConnectionLoggingEnabled 1