Design Patterns in Swift: iOS/macOS

The book "Design Patterns in Swift: iOS/macOS" is a practical guide to applying classic and modern architectural solutions in the Apple ecosystem. Whether you are creating a simple iPhone app or a complex framework for macOS, understanding design patterns will help you write clean, testable, and easily maintainable code.

What is this book about?

The book systematically covers 23 patterns from the GoF (Gang of Four) catalog, adapted to the specifics of the Swift language and iOS/macOS platforms. Each pattern is examined through the lens of real-world tasks that Apple developers face:

• Creational Patterns (Singleton, Factory Method, Builder, etc.) — managing object creation under ARC and multithreading conditions.
• Structural Patterns (Adapter, Decorator, Facade) — organizing classes and structures for working with UIKit, SwiftUI, and Core Data.
• Behavioral Patterns (Observer, Strategy, Command) — implementing reactive interfaces and event handling.
• iOS Architectural Patterns — MVC, MVVM, VIPER, Coordinator with examples of migration between approaches.

Who is this book for?

• iOS/macOS developers with 1+ year of experience who want to improve the architecture of their projects.
• Junior developers aiming to move to the Middle level by understanding SOLID principles and patterns.
• Tech leads looking for ways to standardize code within a team and simplify reviews.
• Developers transitioning from Objective-C to Swift who want to master idiomatic approaches of the new language.

What will you learn?

• How to avoid "spaghetti code" using the Dependency Injection pattern and Protocol-Oriented Programming.
• Why Singleton in Swift is an anti-pattern and what to use instead in modern applications.
• How to implement the Observer pattern using Combine and @Published properties.
• Secrets of building a multi-layered architecture with separation of concerns.
• How to test patterns with XCTest and inject mocks without pain.

Each chapter contains UML diagrams, ready-to-use Swift 5.9+ code snippets, and exercises for reinforcement. The book is suitable both for self-study and as a desktop reference when designing new features.

Ideal for developers who want their applications to run stably and their code not to turn into "technical debt" six months after release.