WWDC19

Table of Contents

=================

• Table of Contents
• Advances in Networking, Part1 - Thursday
  • Low Data Mode
    • URLSession & Network.framework
  • Combine in URLSession
  • WebSocket
    • URLSessionWebSocketTask
  • Mobility Improvements
    • Wi-Fi Assist in iOS 13
    • Multipath Transports

Advances in Networking, Part1 - Thursday

Session materials: https://developer.apple.com/videos/play/wwdc2019/712/

Low Data Mode

• User preference to minimize data usage
  • Explicit signal to reduce network data use
  • Per wifi and cellular network
  • Background tasks are deferred in this mode
  • Background app refresh is also disabled

URLSession & Network.framework

• Try large/prefetch with allowsConstrainedNetworkAccess = false

• On failure with error.networkUnavailableReason == .constrained try low data mode alternative here

• Set prohibitConstrainedPaths on NWParameters
• Check isExpensive in NWPath

Combine in URLSession

.debounce()
.removeDuplicates
.filter {}
.map {}
.sink()

• DataTaskPublisher
  • Single value publisher
  • Similar to URLSession.dataTask

    .tryCatch {}
    .tryMap {}
    .retry(1)
    .replaceError(with)
    .receive(on: Thread)
    .assign(to)
    

WebSocket

• Two-way communication over TLS/TCP connection
• Works with Firewalls and CDNs
• Proxy support

URLSessionWebSocketTask

• Compatible with URLSessionTask

• Server-> NWListener

• Client-> URLSessionWebSocketTask

• Webkit -> Javascript Websocket
• URLSession -> URLSessionWebSocketTask
  • Supports authentication and cookies
• Network.framework -> Webseocket Connection & Listener

Mobility Improvements

Wi-Fi Assist in iOS 13

• Cross-layer mobility detection is built into URLSession and Network.framework

• Rethink SCNetworkReachability usage
• Control access with allowsExpensiveNetworkAccess = false

Multipath Transports

• Apple maps and music are now also using this technology as Siri to have a better transition between cellular & wi-fi