Discover the MVVM Architecture in less than 90 seconds

In this article, you’ll find everything you need to figure out this popular iOS app architecture

You’re more of a video kind of person? Don’t worry: I’ve got you covered 👇

MVVM can feel a bit mysterious when you’ve never used it 😶‍🌫️

But I swear it’s really simple to understand! 😌

In just a few paragraphs we’ll go over everything you need to understand how this architecture works!

Let’s start with this ViewController.

If you think about it, this ViewController actually has a lot of responsibilities!

It must: fetch its data, format its data and then finally display its data 💪

With so many responsibilities, this ViewController will become harder and harder to maintain as our app will grow in complexity 😰

That’s why it makes sense to extract some of these responsibilities to another object called a ViewModel!

So let’s do it in 6 easy steps 🚀

Step 1️⃣, we create the ViewModel

Step 2️⃣, we extract the Service and the Formatter to the ViewModel

Step 3️⃣, we add a callback to update the UI whenever the data gets updated

Step 4️⃣, we move the logic to fetch and format the data to the ViewModel

Step 5️⃣, we provide the ViewController with an instance of the ViewModel

Step 6️⃣, the ViewController can now rely on the ViewModel to fetch and format the data

And that’s it, we’ve successfully implemented a simple version of the MVVM pattern 🥳

Want to experiment for yourself? You get the code here 👇

(https://gist.github.com/vincent-pradeilles/1ffbf87ae9da68ccc723f512f5f5c866)