Comparing VIPER vs. MVVM

Recently I started playing with VIPER architecture. Although I was quite hesitant trying it out, it turns out it's not all that bad as I expected. It'e certainly better than traditional MVC iOS architecture in terms of testability and separation of concerns. However, I found it consistently annoying to have to make bunch of files even for small features. It's after all a price paid to get more testability out of components.

I am still waiting to get all the code uploaded to GitHub. But in meantime I will make a tiny comparison with MVVM to give you a better idea about these two architectural paradigms.

MVVM VIPER
Contains 3 components. Model-ViewModel-View Contains 5 basic View-Interactor-Presenter-Entity-Router
Provides less granular view of components by encapsulating non-view related logic into viewModel Provides more granular view by encapsulating non-view related logic into presenter, interactor and router
View is responsible for routing Router part of components is responsible for routing
MVVM generally uses ReactiveCocoa, RxSwift or equivalent reactive components to communicate VIPER generally uses delegate and protocol pattern to facilitate communication between interactor, presenter and view
Unit testing is performed for View-Models as it contains the main business logic. (You can test views too, but this component is usually detached from View-Model) Unit testing is performed on Presenter and interactor and views
Contains less boilerplate code since all the components are essential in architecture Contains more boilerplate code since in small use-cases developers still have to make presenter, interactor and router even though they may not be necessary
Model part handles network or database models Entity part handles network or database models
Data model layer is associated with ViewModel which performs storing and fetching data from local database cache. ViewModel in turns informs view about any updates in incoming data Data model layer is associated with interactor. Data model informs interactor about data change, which in turns informs presenter. View gets this information from presenter.

I found these differences from my tiny VIPER experience. Let me know if you have additional things to add to list or there are any differences you do not agree with. I would love to hear your thoughts on these architectural differences.

Jayesh Kawli

I am a web and mobile developer working at Wayfair in Boston, MA. I come to learn so many things during course of life and I write about things which helped me and feel like they can help others too.

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