How do you design a scalable iOS networking layer in large applications?

A scalable networking layer is modular, testable, supports retries, caching, and abstracts transport details.

A production-grade networking layer typically separates concerns into API clients, request builders, interceptors (auth, logging), and response decoders. It avoids tight coupling with UI layers. It also supports retry policies, exponential backoff, request cancellation, and dependency injection for testability. Modern implementations use async/await over callback chains and integrate with caching layers (memory + disk).