1. Очень крутая книжка по сетям (стек OSI) – Charles Severance “Introduction to Network: How the Internet works”
2. URLCache – https://nshipster.com/nsurlcache/
3. Ресёрч HTTP-кеширования с использованием URLCache https://qnoid.com/2016/04/10/A-primer-in-HTTP-caching-and-its-native-support-by-iOS.html
4. Анализ доступности сети:
   * SimplePing – https://developer.apple.com/library/archive/samplecode/SimplePing/Introduction/Intro.html
   * https://github.com/dustturtle/RealReachability
   * https://github.com/ankitthakur/SwiftPing
   * https://github.com/lmirosevic/GBPing
   * https://github.com/rwbutler/Connectivity
   * Баг с 2009 года – https://lists.apple.com/archives/macnetworkprog/2009/May/msg00056.html
   * Get IP from hostname – https://gist.github.com/mcgaffin/3873928
   * https://medium.com/@rwbutler/nwpathmonitor-the-new-reachability-de101a5a8835
5. Serial Queue for URLSessions delegates - https://thoughtbot.com/blog/a-simple-approach-to-thread-safe-networking-in-ios-apps
6. Анализ сетевых пакетов – https://medium.com/@MikeFurtak/go-deep-on-ios-packet-analysis-6a7542eeffb3
7. Guide от Apple по анализу сетевых пакетов – https://developer.apple.com/documentation/network/recording_a_packet_trace
8. HTTPPipelining – https://stackoverflow.com/questions/14810890/what-are-the-disadvantages-of-using-http-pipelining
9. Сессии WWDC:
   * 711 2015 Networing with NSURLSession
   * 711 2016 NSURLSession: New Features and Best Practices
   * 709 2017 Advances in Networking
   * 714 2018 Optimizing Your App For Today's Internet

И на правах рекламы свежий и компактный тайм-трекер для повышения личной эффективности – http://hourly-app.com
Вот здесь можно почитать про него на ProductHunt – https://www.producthunt.com/posts/hourly-3