Reference — Comprehensive Network.framework guide covering NetworkConnection (iOS 26+), NWConnection (iOS 12-25), TLV framing, Coder protocol, NetworkListener, NetworkBrowser, Wi-Fi Aware discovery, and migration strategies
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February 3, 2026
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npx add-skill https://github.com/CharlesWiltgen/Axiom/blob/main/.claude-plugin/plugins/axiom/skills/axiom-network-framework-ref/SKILL.md -a claude-code --skill axiom-network-framework-refInstallation paths:
.claude/skills/axiom-network-framework-ref/# Network.framework API Reference ## Overview Network.framework is Apple's modern networking API that replaces Berkeley sockets, providing smart connection establishment, user-space networking, built-in TLS support, and seamless mobility. Introduced in iOS 12 (2018) with NWConnection and evolved in iOS 26 (2025) with NetworkConnection for structured concurrency. #### Evolution timeline - **2018 (iOS 12)** NWConnection with completion handlers, deprecates CFSocket/NSStream/SCNetworkReachability - **2019 (iOS 13)** User-space networking (30% CPU reduction), TLS 1.3 default - **2025 (iOS 26)** NetworkConnection with async/await, TLV framing built-in, Coder protocol, Wi-Fi Aware discovery #### Key capabilities - **Smart connection establishment** Happy Eyeballs (IPv4/IPv6 racing), proxy evaluation (PAC), VPN detection, WiFi Assist fallback - **User-space networking** ~30% lower CPU usage vs sockets, memory-mapped regions, reduced context switches - **Built-in security** TLS 1.3 by default, DTLS for UDP, certificate pinning support - **Mobility** Automatic network transition handling (WiFi ↔ cellular), viability notifications, Multipath TCP - **Performance** ECN (Explicit Congestion Notification), service class marking, TCP Fast Open, UDP batching #### When to use vs URLSession - **URLSession** HTTP, HTTPS, WebSocket, simple TCP/TLS streams → Use URLSession (optimized for these) - **Network.framework** UDP, custom protocols, low-level control, peer-to-peer, gaming, streaming → Use Network.framework #### Related Skills - Use `axiom-networking` for anti-patterns, common patterns, pressure scenarios - Use `axiom-networking-diag` for systematic troubleshooting of connection failures --- ## When to Use This Skill Use this skill when: - **Planning migration** from BSD sockets, CFSocket, NSStream, or SCNetworkReachability - **Understanding API differences** between NWConnection (iOS 12-25) and NetworkConnection (iOS 26+) - **Implementing all 12 WWDC 2025 examples** (TL