GraphQL on Swift: The Complete Guide to Building APIs for iOS and macOS

The book "GraphQL on Swift" is a comprehensive guide to integrating the modern GraphQL query language into the Apple ecosystem. If you're tired of REST, want to fetch only the data you need, and build truly flexible client-server applications — this book is for you.

What is this book about?

The book will take you from the basics of GraphQL to creating production-ready applications in Swift. You'll start with theory: how GraphQL differs from REST, how schemas, types, and resolvers work. Then you'll move on to the practical part — setting up Apollo iOS, writing queries, mutations, and subscriptions.

Special attention is given to:

• Application architecture — how to organize code to work with GraphQL conveniently and scalably.
• Caching and offline mode — Apollo normalized cache, data update strategies.
• Error handling — processing partial responses, schema validation, logging.
• Testing — unit tests for queries, mock servers, UI testing.
• Performance — pagination, batching, image loading via GraphQL.

Who is this book for?

The book is aimed at iOS/macOS developers who are already familiar with Swift and want to master a modern approach to working with APIs. Experience with GraphQL is not required — all concepts are explained from scratch. However, a basic understanding of REST and networking in Swift will be a plus.

The book will be useful both for mobile application developers and backend engineers who want to understand how clients interact with a GraphQL server.

What will you learn?

• How to design an efficient GraphQL schema for your application.
• How to use Apollo iOS — the most popular library for working with GraphQL in Swift.
• How to implement real-time subscriptions (WebSocket).
• How to manage application state using the Apollo cache.
• How to write clean, testable code for working with data.
• How to avoid common mistakes when integrating GraphQL.

Book structure

The book consists of 12 chapters, divided into three parts:

• Part I: Introduction to GraphQL — history, comparison with REST, syntax, tools.
• Part II: GraphQL on the Client — Apollo iOS, queries, mutations, subscriptions, caching, file handling.
• Part III: Advanced Topics — testing, performance, architecture, migration from REST.

Each chapter contains code examples that can be immediately applied in a project. At the end of the book, you'll find an appendix with the complete code of a ready-made iOS application using GraphQL.

This book will become your reliable companion in mastering GraphQL on Swift. Whether you are creating a new application or modernizing an existing one, you will gain practical skills that will immediately improve the quality of your code.