How I Learned To Apply Clean Architecture

About me

I am an iOS developer, product designer, entrepreneur. I focus on creating apps for positive social or individual impact.

iOS is the main technology I worked with, so far. I worked with two agencies early in my career. I later carried that knowledge and did some freelancing. Then I started an app development agency.

Why I wanted to learn Clean Architecture

I believe that almost every iOS developer can launch an app. You can take the graphic design your designer gives you, create a view controller for each screen, mash some business logic in there to make it all integrate with your data and you’re done. Launch!

That’s what I did with Timefly, a product that helped you read relevant news. I launched a product with some cool features in about one month.

I realized that it’s easy to launch a product. Any developer with some basic knowledge can do it. I certainly could, even early in my career, and I enjoyed the speed that I could achieve. That's good. That’s part of how we achieved our technological progress. People created tools that make programming easier.

Later, my client wanted to add a new feature. I said: “Great!” More amazing work to deliver. But wait. I needed to modify some of the code here, add some code in this view controller. It all needed to work well with the previous features as well. No problem. I made it work.

Later my client wanted to add another news data source. Hmm. I mashed that code together and realised that my classes are starting to get bigger and bigger. It was harder to read. I started to forget where I should look to make a change. I needed to run the app, set a breakpoints to take everything step by step and figure out what was happening.

Imagine that you are an electrician and you need to install some new system in the following wiring.

I then made some changes to my code, made everything work and sent another build. Then I got the feedback from my client and some other part of my app didn’t work as it did previously.

At that time I realized that, yes, anyone can launch an app easily. However, it’s not that easy to launch an app, over and over again, consistently, easily, with confidence that you won’t break the older parts of the code. I needed to organize my code. It took me another month to study, refactor and organize my code better. I still didn’t know what I was doing. That’s how I started to learn more about better architecture patterns.

How I approached learning Clean Architecture

It wasn’t a direct learning path. I started to read a lot about different techniques to simplify my view controllers.

First, I experimented with MVVM (Model-View-ViewModel). I started to separate the business logic and other logic from the view controller. I add observers to the view model and make the view react to any changes in the view model. It was a slightly better pattern than MVC, so I applied everywhere.

Then I tried the VIPER pattern. It is much better than MVC and MVVM, as you no longer classify your code into 3 categories. You have 5 categories now: View, Interactor, Presenter, Entity, and Routing. That’s great!

Then I found that Clean Architecture is even better. I read the article that Uncle Bob wrote about Clean Architecture about 5 times. It was still hard to understand. I was still making mistakes, as something always didn’t make sense.

It was a slow learning process for me.

Challenges I faced

At first, I didn’t quite realize the importance of defining very well the application’s Entities and Use Cases. It is incredibly important and you have to get this first process right. As a mobile developer and, especially, as a visual mobile developer, I used UI paradigms to drive my thinking. I still thought of Buttons, Image views, Table views, Gesture recognizers as the main characters of an app. So I planned everything with those details in mind. I was making a crucial mistake.

Entities are the most important components. The use cases are the second most important component as they define certain operations for those entities. Buttons, image views, scroll views, CoreData, they are all details.

Also, in my attempts to get the architecture right, I wanted to test my code automatically, using unit tests. However, I realized that I still wasn’t writing my code to be easy to test. I had to learn to do that better and better, until I achieved a good level of competence and satisfaction.

Key takeaways

I would assume that everyone wants long-term success, not just short-term success. The role of the developer includes a negotiation with the product owner about this. A Clean Architecture is incredibly important to have for an app that wants long-term success. That’s why I’m putting a bet that it’s best to create a Clean Architecture from the start for all apps.

It will save everyone a lot of energy, it makes the app extensible and easy to test. It gives a sense of relief for the developers, as they know exactly where to look when reading, changing, adding or deleting code. They do less debugging.

Tips and advice

This learning journey to create a better and better architecture is all worth it. I would recommend all developers to take it. But don’t do it like I did it. Start directly with learning Clean Architecture. Use Test Driven Development to force you to write better and better code.

Final thoughts and next steps

My next learning goal is to try as many tools as possible that would speed up app testing. This includes unit testing frameworks, UI testing. However, I will always be interested in improving the architecture and making it more and more efficient.