A structured, expert-level book that helps you build robust mobile apps, avoid costly mistakes, and advance your career — without the $300+ course price.
This is an early release edition — buy now at a lower price and get all future updates for free.
More than just a book. This is a multi-volume resource packed with unique insights and expert strategies to accelerate your career.
You will receive the complete book as a single volume for easy reference.
Plus, you’ll also receive the same content in a structured 3-part Expert Edition. These are organized by key stages of mobile system design for easier navigation and focused learning.
All editions are included in both PDF & ePUB formats, read however works best for you.
0. From Briefings To System Architecture (197 pages)
Turn vague requirements into a complete, structured, scalable architecture, while applying fresh, real-world-tested approaches to Dependency Injection and testing.
Learn how to navigate uncertainty, deliver a strong technical foundation from scratch, and build maintainable systems that support fast iteration.
1. Modular UI & UI Architectures (243 pages)
Build UI architectures that scale by designing modular, self-sufficient features.
Learn how to create reusable views that adapt to different navigation patterns, ensure components remain flexible and independent, and structure UI layers for long-term maintainability.
Covers key strategies for balancing reusability with clarity, reducing coupling, and improving testability.
2. Large-Scale Codebases & Design Systems (In progress)
Learn how to implement a design system that balances flexibility with consistency, ensuring seamless UI scalability across teams and products.
Then, discover how to break down a growing codebase into maintainable modules, enforce clear boundaries, and prevent complexity from spiraling out of control.
When preparing for a job interview or navigating your daily work, you don't always have time to read an entire book.
That's why when you buy the book, you'll also get the Quick Reference Guide! This gives you instant access to essential steps for turning vague requirements into clear, complete implementations.
Donny Wals
iOS engineer, Speaker, Author of Practical Concurrency and Practical Combine.
“This book takes a step back to focus on the core principles behind good system design for mobile apps, and really helps to peel back the layers of what good code design should look like.”
Marie Denis
Entrepreneur, Women Make creator, former iOS engineer at Twitter.
“Overall, I found it user-friendly, easy to read. I particularly like the concrete project example, which realistically mirrors a day-to-day work scenario. The approach is practical.”
Hugo Visser
Google Developer Expert for Android, Main robot at Little Robots
“If your team is struggling with code patterns or arguing about architectures, this book provides valuable advice to get back to actually shipping features.”
This book is for mobile engineers who want to deliver stable, robust apps that hold up over time.
It's especially helpful if you're still building features, but want to approach them with clearer architecture and longer-term thinking.
You’ll get the most out of it if:
❝It has helped me crack some of the most difficult System Design interviews.
It's even helping in my current role where I'm heading the mobile division.❞
— @_thatabishek
Part 0: From Briefings to System Architecture
Part 1: Modular UI & UI Architectures
Part 2: Large-Scale Codebases & Design Systems (in progress)
Subject to change, coming in 2025 / 2026 ⬇️
22. From UI Library to Design System; Standardizing UI Decisions with Tokens
23. Nurturing and Growing a Design System
24. Transitioning into a Modular App
25. Large-scale app architectures
26. Quality assurance and testing strategies
Tjeerd has put together the definitive book to building a mobile app for large and small companies alike.
Stop getting stuck in a difficult codebase that's hard to modify. Learn how to keep a growing codebase nimble and easily adjustable so that you can focus on delivering features.
Learn to be more resourceful in your engineering practice when working with constraints, such as dealing with limited information and available time.
Having this newly acquired knowledge will allow you to make swifter and smarter technical decisions for your team or at your company.
You will cover the process of creating a feature from scratch — all the way to delivering large-scale solutions.
Each step of this process is explained in depth and in detail; This approach is tailor-made for the mobile engineer.
The book's process strongly resembles those that exist in a real-life working environment, whether that's a small team or multinational enterprise.
By making use of this practical approach, it allows you to learn tangible skills and knowledge that you can apply to your own work the very next day.
The book is suited for all mobile platforms.
System Design is becoming an increasingly standard aspect of the interview process and a responsibility of mobile engineers in terms of their expected skillset and competencies.
Use this book to build on your current skills to improve your day-to-day work and prove that you can handle difficult requirements for mobile apps.
Confidently move away from building small features by showing that you can deliver app-wide solutions.
Access 21 out of 26 chapters now.
Get the full book upon completion!
What you'll get:
Includes all of this:
I have a system design interview coming up for iOS in about 3 weeks. Anyone available to help me practice? I’ve been reading this https://t.co/hbUETCKrrj and it’s been very helpful :)
— Taylor Simpson (@phzytaylor) January 22, 2024
Exploring @tjeerdintveen's https://t.co/byhJdiTZiS for the second time as it updates. It's a valuable resource for mobile engineers at any level, significantly aiding my project work. Even received direct help from Tjeerd on an occasion! #MobileEngineering #iOS
— Edvinas Gestautas (@edvinasges) February 2, 2024
Tjeerd in ’t Veen is a mobile engineer who challenges the way we create mobile applications.
With over 25 years of experience developing features, including roles as a staff engineer at Twitter (now X) and as a mobile tech lead at ING international bank, he possesses expertise in developing mobile applications with scalability, adaptability, and robustness.
Tjeerd is the author of the highly-rated book Swift in Depth.
Connect with Tjeerd
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Why is this book priced lower right now?
This is an early access price while the book is still in progress. As more chapters are added and the book is finalized, the price will increase. By buying now, you lock in the lower price and get all future updates for free.
What is an early release edition?
This book is a work in progress, each chapter is released one by one. If you buy the book today, you will be able to read all finished chapters. Once the book is finished, you will get the definitive, edited, book containing all chapters.
What is System Design, is it UI related?
System Design is about technical design. It's about coming up with all the components, API's, and architecture necessary to make a mobile app work. This book will cover the technical design of various components across multiple abstractions and domains.
Is there UI in this book?
This is not a traditional "UI Book" where we cover components and how to style them.
However, the book does cover many important topics related to UI. Such as adding a design system to a pre-existing project (just like real life), delivering reusable components, component abstractions, and how to reason about UI architectures.
Is this book focusing on interviews or building an app?
It assists you with both. In this book we'll go over the processes of turning requirements into a robust feature all the way to a modular codebase. Along the way you'll learn mental models that you can apply to your own application and interviews.
This book is not a template to common approaches however. The books' aim is to give you tools so you can solve any problem, not just pre-rehearsed problems.
This way, you can handle any problem that's thrown at you during the system design interviews.
I'm preparing for an interview. What should I read first?
Start with the Quick Reference Guide, included as a bonus when you buy the book. It offers concise, actionable tips to help you quickly prepare and feel confident.
Is this book for Android, Flutter, or iOS engineers?
All mobile engineers! That includes Android, iOS, Flutter, and Hybrid solutions such as React Native.
The book uses iOS and Swift as a vehicle to explain concepts and best practices. Where necessary, the book explains specific Swift keywords.
If you’re Android engineer: Rest assured that Swift reads similar to Kotlin in many ways. With little effort, you'll be able to understand the Swift code examples.
If I already make apps, is this book for me?
Absolutely. The book assumes you're already a developer working on apps, or about to become one. If you’re a senior or junior engineer, then this book is written for you.
I have never even made an app, is this book for me?
The book is aimed at people that have at least some experience in the app-development world. However, if you've never made an app before, this book will show you what the process entails.
Is this an eBook or printed book?
This is a digital eBook, provided in both ePUB and PDF formats. You’ll receive the complete book as a single volume, plus a 3-book structured edition, all available in both formats for flexible reading.
What’s the difference between the complete book and the structured edition?
You get the same content in both versions, but the structured edition organizes the book into three focused books to make it easier to read and apply in stages. The single-volume complete book is great for reference, while the structured edition helps with step-by-step learning.
Do I need to read all three books separately?
You can read however works best for you. If you prefer a step-by-step learning approach, the structured edition helps you focus on each stage of mobile system design. If you like having everything in one place, the full book is available as a single volume.
Can I skip a chapter, or do I need to read them in order?
You can start wherever works best for you, but the real power of this series is that each book and chapter builds on the same project. By following the structured edition from start to finish, you’ll see how the concepts come together in a practical, real-world way. It's a journey starting from scratch to helping you design robust systems with confidence. That said, if you’re already experienced in certain areas, you can jump to the section that’s most relevant to you.
Is there different content in the structured edition?
The core chapters are the same as in the full book, but the structured edition includes exclusive introductions and conclusions for each part. These custom intros and outros provide extra guidance on how each section fits into the bigger picture, helping you learn and apply concepts more effectively.
Will there be a printed book version?
It is being considered. But the initial goal is to make the eBook available first.
Is this a programming book?
Sort of, but not really. The book covers the process of developing a mobile application. However, it's not a "code book". The book uses Swift to show concepts and how to implement something on a code-level. But it won't show you how to make a complete app from scratch.
It uses code as a vehicle to explain ways of thinking and how to get things done. But this book is more about mental models and avoiding pitfalls. It's about making better choices at every step of the process. From a requirement to a full-fledged, tested, implementation.
What does the subtitle “Resourceful engineering" entail ?
Developing a mobile application has a wide range of topics, from building a small view to maintaining a giant modularized application using a variety of tooling. The term "system design" can encompass even more, from interviews, to architectures, to shared code solutions such as hybrid, a Rust core layer, or Kotlin Multiplatform.
With Resourceful Engineering we refer to a very common, yet local, process in an app codebase, which is 'getting requirements and having to deliver a solution, features, and various components'
In reality, this means you have to move forward despite not knowing all the answers. Making strong choices with limited information is key.
To be resourceful means to be making the best out of the situations with the limited resources that you have.
In this case, that means you will learn to make good decisions at each step of the feature development process. During this process, we’ll try to get all the answers, find the hidden details, and work in such a way, so that our code can adapt to new (unforeseen) requirements.
Can I generate an invoice after buying this book?
Yes! Read how on Lemon Squeezy's guide.
Help, I can’t afford this book!
If you’re a student or in an unemployed situation, contact me at [email protected], and we can talk options and discounts.
What if I buy it and don't like it?
Send an email to [email protected] within 15 days from the purchase and you will get a refund. No questions asked.
Access 21 out of 26 chapters now.
Get the full book upon completion!
What you'll get:
Includes all of this: