A functional and colorful task / to-do list app built with Kotlin Multiplatform Mobile (KMM)
Looking for the web app or server backend?
My main goal with this project was to teach myself Jetpack Compose. I also wanted to go through the process of creating a KMM-compatible app, with the eventual goal of using the same shared code on both iOS and Android devices.
I've previously built apps with Retrofit, Room, and Hilt, but I realized that a KMM app presents a unique set of challenges, and would require libraries explicitly compatible with it.
For this project, I settled on:
- SQLDelight (caching data)
- Jetpack DataStore (persisting user preferences)
- Koin (dependency injection)
- Ktor (REST API consumption)
- Firebase / Crashlytics
New as of August 2023:
- JetBrains Compose (cross-platform declarative UI)
- Decompose (UI state tree model)
Recently, I've rewritten the app using JetBrains Compose Multiplatform! This means that 99% of app UI and business logic is now shred between devices, and the app now sports the same colorful look and feel on both platforms!
For UI state management, I decided to use Decompose and split the shared code into multiple modules:
- Shared
- Model
- Database (SQLDelight generated database classes)
- Data (Repository, data layer)
- Domain (common client-side logic)
- Component (w/ Decompose)
- UI (w/ JetBrains Compose)
- Ext (interfaces for app functionality required by other modules)
- Framework (exports a framework for Xcode/SwiftUI to use)
My goal with the app's design was to be functional and colorful, mirroring the features available in Google Tasks and Microsoft To-Do while utilizing my interpretation of the Material You design language. I'm proud of how it's turned out thus far 😄
Currently, the app includes:
- Multiple task lists
- Tasks with multiple fields
- List customization options
- Reminder push notifications
- A helpful dashboard for starred and upcoming tasks
- Cross-device sync and an account system
There are a few things I have yet to implement, mainly:
- List sharing
- Widgets
- Subtasks
- Recurring tasks
The backend server was concurrently designed with the app, using many of the same libraries (mainly SQLDelight and Ktor) as the client code. You can view the code here.
I built the app to be extensible where possible, but some cross-cutting refactors have been unavoidable. To avoid loss of test user data, I used SQLDelight migrations on both the client and the backend.
If I were to start this project over, there are two major things I'd do differently:
- I'd use Source Control (Git) from the beginning and practice a more Agile development cycle.
- I'd add unit and integration testing to the list of concepts to teach myself during the project.
For code linting before each commit, change the project's git hooks directory with this command:
git config core.hooksPath hooks/You can also copy the contents of /hooks to your project's git hooks folder.