Steller

This demo app contains some best practices for iOS app development in Swift:

Clean architecture
Single-point Environment-based dependency injection
Theming
Localization
Unit tests
Data mocking for testing and SwiftUI previews
UIKit -> SwiftUI conversions
Custom SwiftUI elements
Basic animations
State-based routing

Architecture

In this branch the Steller demo app is implemented using a Uncle Bob's Clean Architecture principles and heavily inspired by this Medium article by Alexey Naumov: https://medium.com/swlh/clean-architecture-for-swiftui-6d6c4eb1cf6a

Key differences between this implementation of Clean Architecture and MVVM

In Clean Architecture the ViewModel from the MVVM breaks down to: Interactor (business logic), Repository (data requests).
View breaks down to the View and Router.

For such a small demo the Clean Architecture is a bit of an overkill, especially when implemented from scratch. In this repo, you can find also a MVVM version, much easier to implement and understand for new developers.

Benefits over MVVM

So why Clean Architecture?

Greater separation of concerns

Almost 100% testability.
Dependency injection.
As the project gets bigger, things are easier to find and debug.

Unidirectional flow of data

It's easier to test and find bugs.
Elimination of race conditions.

Routing

Unfortunately, SwiftUI doesn't come with a clear way of providing navigation outside of NavigationView which is not very customizable at the moment.
By introducing a centralized routing system, I attempt to solve the issue, opening the doors to handling URLs for deep linking and a clear testable state-based navigation.