How to interact with screen in KMP module, from native Android app.

[marenovakovic]

App in mids of migration from native Android to KMP + Compose Multiplatform.
Has screen defined in shared commonMain KMP module.
How to contribute to building Circuit from KMP commonMain?
How to navigate to said KMP screen inside commonMain from native Android screen?

[ZacSweers]

Sorry I'm not sure I understand what you're asking, can you be more specific?

[marenovakovic]

Sorry, my bad.

I solved the issue in a meanwhile.

Issue was:

I had problems integrating screens from shared multiplatform (KMP) module into existing Android app.
My hacky solution, providing separate Circuit for KMP and Android screens, worked when there was only one screen from KMP module that needed to be shown.
Once I got to a point when I needed to navigate to second KMP screen I was getting Route not available error.

Hacky solution:

val circuit = when (screen) {
  SharedKMPScreen -> LocalSharedCircuit.current
  else -> LocalCircuit.current
}
CircuitContent(
screen = screen,
modifier = Modifier.padding(innerPadding),
circuit = requireNotNull(circuit),
key = screen::class,
)

Android app uses Dagger, @CircuitInject, etc. and there is nice auto-generated code for Ui and Presenter factories.
I couldn't figure out how to add additional factories, for screens located inside KMP module, to this process.
Circuit was unaware of all some screens existence.

Solution:

Dependency injection for KMP module is using kotlin-inject and what I did is adding separate Dagger module to bridge the gap between Dagger and kotlin-inject.
This glue module takes kotlin-inject component that's providing all Ui and Presenter factories for KMP screens.
Inside glue module:

@Provides
@ElementsIntoSet
@SingleIn(AppScope::class)
fun presenterFactories(): Set<Presenter.Factory> = component.presenterFactories

@Provides
@ElementsIntoSet
@SingleIn(AppScope::class)
fun uiFactories(): Set<Ui.Factory> = component.uiFactories

@ElementsIntoSet solved the issue since it merged Android and KMP factories together allowing for easy Circuit creation:

@Provides
    fun provideCircuit(
      presenterFactories: DaggerSet<Presenter.Factory>,
      uiFactories: DaggerSet<Ui.Factory>
    ): Circuit {
      return Circuit.Builder()
        .addPresenterFactories(presenterFactories)
        .addUiFactories(uiFactories)
        .build()

Once Circuit was aware of all screens involved navigation wasn't an issue any more.