Android KMM Strategies

ExampleViewModel.kt

public class ExampleViewModel : ViewModel() {
    private val state = mutableStateFlowOf(ExampleFragmentState())
    
    public fun observeStates(): StateFlow<ExampleFragmentState> = state.asStateFlow()
    
    public fun button1Clicked() = viewModelScope.launch { 
        // ...        
    }
    
    public fun button2Clicked() = viewModelScope.launch { 
        // ...
    }
}

KmmCompose.kt

@AndroidEntryPoint
class ExampleFragment : ComposeFragment() {

    private val viewModel: ExampleViewModel by viewModels() // shared ViewModel, injected by Hilt

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return ComposeView(requireContext()).apply {
            setContent {
                MaterialTheme {
                    val uiState by viewModel.observeStates().collectAsState() // data is emitted from the shared ViewModel with a StateFlow
                    ExampleContent(uiState)
                }
            }
        }
    }

    @Composable
    fun ExampleContent(
        state: ExampleFragmentState
    ) {
        Text("${state.count}")
        
        Button(onClick = { viewModel.button1Clicked() }) { 
            Text("Button 1")
        }
        Button(onClick = { viewModel.button2Clicked() }) { 
            Text("Button 2")
        }
    }
}

KmmXmlViews.kt

@AndroidEntryPoint
class ExampleFragment : ComposeFragment() {

    private val viewModel: ExampleViewModel by viewModels() // shared ViewModel, injected by Hilt

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        return ExampleFragmentBinding
            .inflate(inflater, container, false)
            .also { binding = it }
            .root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        // data is emitted from the shared ViewModel with a StateFlow
        lifecycleScope.launchWhenResumed {
            lifecycle.repeatOnLifecycle(Lifecycle.State.RESUMED) {
                viewModel.observeStates()
                    .onEach { state -> binding?.updateWithState(state) }
                    .launchIn(this)
            }
        }
    }

    override fun onDestroyView() {
        super.onDestroyView()
        binding = null
    }

    private fun ExampleFragmentBinding.updateWithState(state: ExampleFragmentState) {
        textView.text = "${state.count}"

        btn1.setOnClickListener { viewModel.button1Clicked() }
        btn2.setOnClickListener { viewModel.button2Clicked() }
    }
}