Goodbye RxSwift 👋🥲

[pchmelar]

📝 Description

• This PR removes RxSwift dependency and refactors the rest of the app into SwiftUI + MVI + async/await 🚀

💡 What’s new?

• All UseCases + Repositories are now using async/await instead of RxSwift
• All views are now in SwiftUI and all view models are using MVI pattern
• LocationProvider protocol and SystemLocationProvider implementation (we were using CLLocationManager directly in the LocationRepository, which wasn't right in terms of Clean Architecture)
• More granular Error handling (take a look at AuthError and ValidationError)
• AppTheme is now using SwiftUI.Color and SwiftUI.Font (instead of UIColor and UIFont)
• BaseHostingController for defining common background color and back button title
• Reusable UserView and PrimaryProgressView

😶 What’s missing?

• Fix KMP
• Because I wanted to finish this ASAP in order to work on more important problems (modularisation etc) I didn't replace all of the functionality we had in UIKit views. Mainly there are no examples of pull-to-refresh and paging, we should add them in next PRs.

📚 References

• https://www.swiftbysundell.com/articles/async-sequences-streams-and-combine/
• https://www.andyibanez.com/posts/using-asyncsequence-in-swift/
• https://github.com/AsyncSwift/AsyncLocationKit
• https://serialcoder.dev/text-tutorials/swiftui/progressview-in-swiftui/

[pchmelar]

I fixed all tests to reflect the changes. There were some minor issues along the way.

• I had to provide a manual mock for DatabaseProvider. Although SwiftyMocky supports generics, it is needed to add additional comparators to Matcher instance, which seems overly complicated. In the end, we aren't using SwiftyMocky that much, so maybe we can take a step back and use just underlying Sourcery for a mock generation. 🤔
• Our ViewModels have .onAppear that can load some data asynchronously via Task. However, as .onAppear doesn't return anything (compared to .onIntent) we can't await its completion in the tests. Fortunately, we have an array of all running tasks in BaseViewModel, so we can use a little workaround in tests:

for task in vm.tasks { await task.value }