Modularizing Swift Apps with SPM

The article explains how to modularize growing Swift iOS apps using Swift Package Manager by dividing the app into three layers: Common (utilities), Services (API and Domain), and Features (UI). This structure enforces strict dependency rules, improving build times and code maintainability by preventing cyclical dependencies. The API module defines server contracts, the Domain module handles business logic and mappings between API and app models, and the Feature modules contain SwiftUI views using only domain models. The author provides sample code and patterns that promote clear boundaries and testability within this modular architecture.