part-1.md

Koin (Part 1)

Get dependencies

https://insert-koin.io/docs/setup/koin/#koin-bom

implementation(platform("io.insert-koin:koin-bom:$koin_version"))
implementation("io.insert-koin:koin-android")
implementation("io.insert-koin:koin-core-coroutines")
implementation("io.insert-koin:koin-androidx-workmanager")

Initialise Application class

• Create application class annotation. We will use this in the last step.

  class BaseApplication: Application() {
      override fun onCreate() {
          super.onCreate()
      }
  }
  

• Add to manifest.

  <manifest ...
    >
  
    <application
        android:name=".BaseApplication"
        ...
        >
  
        ...
  
    </application>
  
  </manifest>
  

Create classes to be injected

1. An API class that will be injected in a repository.

   class MyApi() {
       fun callNetwork()
   }
   

2. A repository interface and its implementation that will be injected in a viewmodel.

   interface MyRepo {
       fun doNetworkCall()
   }
   class MyRepoImpl(
       private val myApi: MyApi
   ): MyRepo() {
       override fun doNetworkCall() {
           myApi.callNetwork()
       }
   }
   

3. A viewmodel to be injected in an activity.

   class MainViewModel(
       private val repo: MyRepo
   ): ViewModel(){
       fun doNetworkCall(){
           repo.doNetworkCall()
       }
   }
   

Create how to inject

Create a file AppModule.kt.

val appModule = module {
    single {
        // create MyApi using Retrofit or something else
        Retrofit.Builder()
            .baseUrl("https://something")
            .addConverterFactory(MoshiConverterFactory.create())
            .build()
            .create(MyApi::class.java)
    }
    // OLD
    //single<MyRepo> {
        // Provide an implementation of MyRepo.
        // "get()" will automatically fetch the api from above "single" block.
        MyRepoImpl(get())
    //}
    singleOf(::MyRepoImpl) { bind<MyRepo>() }
    viewModel {
        // Notice different block for viewmodel
        MainViewModel(get())
    }
}

Inject into activity

class MainActivity: ComponentActivity() {
    private val viewModel: MainViewModel by inject()
}

Inject something not a viewmodel

In this example we inject MyApi just for representation.

class MainActivity: ComponentActivity() {
    //...
    private val api: MyApi by inject()
}

Start koin in the Application class

class BaseApplication: Application() {
    override fun onCreate() {
        super.onCreate()
        startkoin {
            androidContext(this)
            modules(appModule)
        }
    }
}

Done !