MVIJetpackComposeActivity.kt

class MVIJetpackComposeActivity : AppCompatActivity() {

    lateinit var myViewModel: MVIJetpackComposeViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        myViewModel = // factory to instantiate viewmodel
        // just call setContent once
        setContent {
            CraneWrapper {
                App(myViewModel)
            }
        }
}
    
@Composable
fun App(model: MVIJetpackComposeViewModel) {
    MaterialTheme {
        Scaffold(appBar = { MyAppBar() }) {
            // observe the viewmodel here. compose will recompose when it changes.
            val viewState = +observe(model.viewState)
            viewState?.buildUI()
        }
    }
}

@Composable
fun MyAppBar() {
    Row {
        Text(text = "MVI Jetpack Compose App", style = +themeTextStyle { h4 })
    }
}
    
// general purpose observe effect. this will likely be provided by LiveData. effect API for
// compose will also simplify soon.
fun <T> observe(data: LiveData<T>) = effectOf<T?> {
    val result = +state<T?> { data.value }
    val observer = +memo { Observer<T> { result.value = it } }

    +onCommit(data) {
        data.observeForever(observer)
        onDispose { data.removeObserver(observer) }
    }

    result.value
}