Kotlin Mobile Multiplatform App (Android & iOS)
One Code To Rule Them All. Application example using Kotlin Multiplatform and MVVM pattern for both platforms.
Is used:
- layered clean architecture
- DI (Kodein)
- coroutines
- livedata
- ktor
- serialization
- mockk
- detekt, ktlint
- unit tests and jacoco
Presentation layer (Android & iOS)
On both platforms (Android and iOS), we only need to implement an observer in which to process states. Further implementation on Android (Kotlin) and iOS (Swift):
Android
class MainActivity : AppCompatActivity() {
private lateinit var viewModel: IndexesViewModel
private var adapter: IndexesAdapter = IndexesAdapter { viewModel.getQuote(it.ticker) }
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
recycler.adapter = adapter
viewModel = ViewModelProviders.of(this).get(IndexesViewModel::class.java)
observeViewState()
viewModel.getMajorIndexes()
}
private fun observeViewState() {
viewModel.getViewData.addObserver { updateViewState(it) }
}
private fun updateViewState(state: IndexesViewState) = runOnUiThread {
when (state) {
is Loading -> {
Toast.makeText(this, "Loading...", Toast.LENGTH_SHORT).show()
}
is Error -> {
Toast.makeText(this, state.message, Toast.LENGTH_LONG).show()
}
is ShowMajorIndexes -> {
adapter.items = state.indexes
}
is ShowQuote -> {
Toast.makeText(this, state.quote.dayLow + " - " + state.quote.dayHigh, Toast.LENGTH_LONG).show()
}
}
}
}iOS
class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
@IBOutlet weak var tableView: UITableView!
private var viewModel: IndexesViewModel!
internal var indexes: [Index] = []
override func viewDidLoad() {
super.viewDidLoad()
tableView.dataSource = self
tableView.delegate = self
viewModel = IndexesViewModel()
observeViewState()
viewModel.getMajorIndexes()
}
func observeViewState() {
viewModel.getViewData.addObserver { (state) in
self.updateViewState(state: state as! IndexesViewState)
}
}
func updateViewState(state: IndexesViewState) {
switch state {
case is Loading:
view.displayToast("Loading...")
case is Error:
view.displayToast("Error")
case is ShowMajorIndexes:
let successState = state as! ShowMajorIndexes
update(list: successState.indexes)
case is ShowQuote:
let successState = state as! ShowQuote
view.displayToast(successState.quote.dayLow + " - " + successState.quote.dayHigh)
default: break
}
}
...
deinit {
viewModel.onCleared()
}
}Presentation Layer - ViewModels (Shared Code)
This layer is shared by Android and iOS, and this is developed on Kotlin. Here is where we have to call the different use-cases of the domain layer. To make the call async we are using kotlin coroutines and flow.
class IndexesViewModel : BaseViewModel() {
private val getIndexesUseCase by Injector.instance<GetIndexesUseCase>()
private val getQuoteUseCase by Injector.instance<GetQuoteUseCase>()
var getViewData = MutableLiveData<IndexesViewState>(Empty)
fun getMajorIndexes() = launchInMain {
getIndexesUseCase()
.onStart { getViewData.postValue(Loading) }
.flowOnBackground()
.catch { getViewData.postValue(Error("Something went wrong")) }
.collect { getViewData.postValue(ShowMajorIndexes(it)) }
}
fun getQuote(symbol: String) = launchInMain {
getQuoteUseCase.invoke(symbol)
.onStart { getViewData.postValue(Loading) }
.flowOnBackground()
.catch { getViewData.postValue(Error("Something went wrong")) }
.collect { getViewData.postValue(ShowQuote(it)) }
}
}Domain Layer — Models & UseCases (Shared Code)
In this layer, we defining the models and all the use cases that we need for our application.
Data Layer — Repository Pattern (Shared Code)
For this layer we are using a repository pattern. We defining the entity models and all source of our data
For networking we are using Ktor and for JSON deserialisation Kotlinx serialization.
Running unit tests
- Android test: ./gradlew testDebugUnitTest
- Common test on iOS (need run Simulator iPhone 8): ./gradlew iosUnitTest
Running the app
To run the application use the same tools you use in Android and iOS. Just open the project with Intellj/Android Studio for the Android project and XCode for the iOS one.
Screenshots
| Android | iOS |
|---|---|
 |
 |