To-Do

A Kotlin Multiplatform to-do list app with SwiftUI and Compose UI frontends

🎶
Making a list
Checking it twice
Gonna try out declarative UIs
🎵

Disclaimer

I'm just starting to learn my way around both Compose and SwiftUI so the code here can probably be improved on.

Shared code

The core logic in the shared module is implemented via SqlDelight in ToDo.sq. This is exposed in a Kotlin API by ToDoRepository.

In addition to pure common code, there are some iOS-specific helpers. Since suspend functions and Flows aren't available to Swift, FlowAdapter is a slightly modified version of the pattern I presented in my Working with Kotlin Coroutines and RxSwift blog post. A wrapper class ToDoRepositoryIos then exposes iOS-friendly versions of ToDoRespository's API.

Unit tests verify the happy path for both repository classes, making use of the Turbine library for testing Flows. Not a whole lot new there if you're used to testing KMP code, but they're there to look at nonetheless.

Android code

The Android app in the androidApp modules is a single activity ToDoActivity which injects a ToDoRepository into composable views defined in ToDoComposables.kt. There is a fully interactable preview function ToDoListPreview() which exercises the UI without any dependence on the shared code by manually wiring in-memory state

iOS code

The iOS app in the iosApp directory consumes the repository in SceneDelegate.swift, and renders it via SwiftUI views defined in ToDoViews.swift. There is a fully interactable preview view defined in ToDoList_Previews which exercises the UI without any dependence on the shared code by manually wiring in-memory state.

The SwiftUI code makes use of some Combine helpers defined in CombineAdapters.swift in order to translate FlowAdapter to a Published value that SwiftUI can subscribe to. It also converts the Kotlin ToDo class to a Swift ToDo struct via utilities in ToDo.swift. This better matches typical Swift development practices, and it means that the SwiftUI views have no direct dependence on the Kotlin code, which apparently helps the preview work better.