Dagger AssistedInject + ViewModel

DI.kt

import com.squareup.inject.assisted.dagger2.AssistedModule
import dagger.Module

@Component(
    modules = [ViewModelAssistedFactoriesModule::class] // <--- Add assisted module
)
interface SampleComponent {

    fun inject(fragment: SampleFragment)

    //...
}

@AssistedModule
@Module(includes = [AssistedInject_ViewModelAssistedFactoriesModule::class])
abstract class ViewModelAssistedFactoriesModule

extensions.kt

@MainThread
inline fun <reified VM : ViewModel> Fragment.viewModels(
    crossinline viewModelProducer: () -> VM
): Lazy<VM> {
    return lazy(LazyThreadSafetyMode.NONE) { createViewModel(viewModelProducer) }
}

@MainThread
inline fun <reified VM : ViewModel> Fragment.createViewModel(
    crossinline viewModelProducer: () -> VM
): VM {
    val factory = object : ViewModelProvider.Factory {
        @Suppress("UNCHECKED_CAST")
        override fun <VM : ViewModel> create(modelClass: Class<VM>) = viewModelProducer() as VM
    }
    return ViewModelProviders.of(this, factory).get(VM::class.java)
}

presentation.kt

class SampleViewModel @AssistedInject constructor(          // <--- Use AssistedInject instead of Inject
    @Assisted private val assistedArg: String
) : ViewModel() {

    fun doSomething() {
        Log.d("Assisted", assistedArg)
    }

    @AssistedInject.Factory                                 // <--- Create factory
    interface Factory {
        fun create(assistedArg: String): SampleViewModel
    }
}

class SampleFragment : Fragment() {

    @Inject
    lateinit var viewModelFactory: SampleViewModel.Factory // <--- Inject your factory. Not ViewModelProvider.Factory

    private val viewModel by viewModels { viewModelFactory.create("Sample Arg") }
}