axiom-networking

Network.framework Networking

When to Use This Skill

Use when:

• Implementing UDP/TCP connections for gaming, streaming, or messaging apps
• Migrating from BSD sockets, CFSocket, NSStream, or SCNetworkReachability
• Debugging connection timeouts or TLS handshake failures
• Supporting network transitions (WiFi ↔ cellular) gracefully
• Adopting structured concurrency networking patterns (iOS 26+)
• Implementing custom protocols over TLS/QUIC
• Requesting code review of networking implementation before shipping

Related Skills

• Use axiom-networking-diag for systematic troubleshooting of connection failures, timeouts, and performance issues
• Use axiom-network-framework-ref for comprehensive API reference with all WWDC examples

Example Prompts

1. "How do I migrate from SCNetworkReachability? My app checks connectivity before connecting."

2. "My connection times out after 60 seconds. How do I debug this?"

3. "Should I use NWConnection or NetworkConnection? What's the difference?"

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Red Flags — Anti-Patterns to Prevent

If you're doing ANY of these, STOP and use the patterns in this skill:

❌ CRITICAL — Never Do These

1. Using SCNetworkReachability to check connectivity before connecting

// ❌ WRONG — Race condition
if SCNetworkReachabilityGetFlags(reachability, &flags) {
    connection.start() // Network may change between check and start
}

Why this fails Network state changes between reachability check and connect(). You miss Network.framework's smart connection establishment (Happy Eyeballs, proxy handling, WiFi Assist). Apple deprecated this API in 2018.

2. Blocking socket operations on main thread

// ❌ WRONG — Guaranteed ANR (Application Not Responding)
let socket = socket(AF_INET, SOCK_STREAM, 0)
connect(socket, &addr, addrlen) // Blocks main thread

Why this fails Main thread hang → frozen UI → App Store rejection for responsiveness. Even "quick" connects take 200-500ms.

3. Manual DNS resolution with getaddrinfo

// ❌ WRONG — Misses Happy Eyeballs, proxies, VPN
var hints = addrinfo(...)
getaddrinfo("example.com", "443", &hints, &results)
// Now manually try each address...

Why this fails You reimplement 10+ years of Apple's connection logic poorly. Misses IPv4/IPv6 racing, proxy evaluation, VPN detection.