ios-networkinglisted

# iOS Networking Use URLSession with async/await and structured concurrency for ordinary HTTP, REST, uploads, downloads, and streaming. Use Network.framework for lower-level protocols and delegate/task APIs for durable background transfers. ## Contents - [Core URLSession async/await](#core-urlsession-asyncawait) - [API Client Architecture](#api-client-architecture) - [Error Handling](#error-handling) - [Pagination](#pagination) - [Network Reachability](#network-reachability) - [Configuring URLSession](#configuring-urlsession) - [App Transport Security (ATS)](#app-transport-security-ats) - [Common Mistakes](#common-mistakes) - [Review Checklist](#review-checklist) - [References](#references) ## Core URLSession async/await URLSession gained native async/await overloads in iOS 15. Prefer these for foreground data, upload, download, and streaming work. Background URLSession transfers are the main exception: they still use task/delegate APIs so the system can deliver events after suspension or relaunch. Validate networking policy locally with `URLProtocol` fixtures for valid 2xx, malformed 2xx, one-time 401 refresh, bounded 429/5xx retry, timeout/offline, cancellation, and nonretryable 4xx. Inspect headers, status, and error classification; fix the policy and rerun. Retry only safe/idempotent or explicitly replayable requests, and never loop token refresh. ### Data Requests ```swift // Basic GET let (data, response) = try await URLSession.shared.data(from: url) // With a