Async Swift (iOS/macOS): The Complete Guide

The book "Async Swift (iOS/macOS): The Complete Guide" is a comprehensive practical guide for developers who want to master all modern approaches to asynchronous programming on Apple platforms. Whether you are working on applications for iOS, iPadOS, or macOS, understanding asynchrony is a key skill for creating responsive, performant, and safe applications.

What this book is about

The book systematically covers all the main topics:

• Fundamentals of asynchronous programming — what are threads, queues, synchronous and asynchronous operations, data race problems, and locks (deadlock, livelock).
• Grand Central Dispatch (GCD) — working with DispatchQueue, DispatchGroup, DispatchSemaphore, QoS classes, creating custom queues, and avoiding common mistakes.
• OperationQueue and Operation — managing dependencies between tasks, priorities, canceling operations, and reusing them.
• Swift Concurrency (Async/Await) — starting with the basics of async/await, Task, TaskGroup, delayed tasks, structured and unstructured concurrency.
• Actors — protecting mutable state, data isolation, reentrancy, Sendable, and @MainActor.
• Combine Framework — working with Publishers, Subscribers, Subjects, transformation operators, error handling, and canceling subscriptions.
• Practical cases — loading and caching images, networking, updating UI, handling user input, and background tasks.
• Testing and debugging — writing asynchronous tests, using XCTestExpectation, debugging with Instruments, detecting memory leaks and race conditions.

Who this book is for

• iOS/macOS developers who want to transition from legacy approaches (GCD, delegates, closures) to modern Swift Concurrency.
• Junior and Middle developers looking to systematize their knowledge of asynchrony and avoid common mistakes.
• Senior developers who need a reference for best practices, patterns, and performance.
• Students and beginners already familiar with the basics of Swift but not yet experienced with multithreading.

What you will learn after reading

• How to correctly choose between GCD, OperationQueue, Async/Await, and Combine.
• How to avoid data races, deadlocks, and memory leaks.
• How to write safe and maintainable asynchronous code using Actors.
• How to efficiently manage background tasks and update the UI.
• How to test asynchronous code and catch hard-to-reproduce bugs.

The book contains numerous code examples ready for use in real projects. All examples are tested on the latest versions of Swift and Xcode. This is not just theory — it is a practical tool that will help you write fast, reliable, and modern applications for the Apple ecosystem.