What is KOIN?

A pragmatic lightweight dependency injection framework for Kotlin developers.

Written in pure Kotlin, using functional resolution only: no proxy, no code generation, no reflection.

Koin is a DSL, a light container and a pragmatic API

Official Website 👉 https://insert-koin.io

Koin 2.0 is out: https://medium.com/koin-developers/ready-for-koin-2-0-2722ab59cac3

Contact & Latest News 🌐

Follow us on Twitter for latest news: @insertkoin_io
Koin developers on Medium: koin developers hub

Getting Help 🚒

Any question about Koin usage?

Come talk on slack #koin channel
Post your question on Stackoverflow - #koin tag

Reporting issues 🛠

Found a bug or a problem on a specific feature? Open an issue on Github issues

Koin 1.0 docs - https://old.insert-koin.io

Setup

Current Version

// latest stable
koin_version = '2.0.1'

Gradle

Jcenter

Check that you have the jcenter repository.

// Add Jcenter to your repositories if needed
repositories {
	jcenter()    
}

Dependencies

Pick one of your Koin dependency:

Core features

// Koin for Kotlin
implementation "org.koin:koin-core:$koin_version"
// Koin extended & experimental features
implementation "org.koin:koin-core-ext:$koin_version"
// Koin for Unit tests
testImplementation "org.koin:koin-test:$koin_version"
// Koin for Java developers
implementation "org.koin:koin-java:$koin_version"

Android

// Koin for Android
implementation "org.koin:koin-android:$koin_version"
// Koin Android Scope features
implementation "org.koin:koin-android-scope:$koin_version"
// Koin Android ViewModel features
implementation "org.koin:koin-android-viewmodel:$koin_version"
// Koin Android Experimental features
implementation "org.koin:koin-android-ext:$koin_version"

AndroidX

// Koin AndroidX Scope features
implementation "org.koin:koin-android-scope:$koin_version"
// Koin AndroidX ViewModel features
implementation "org.koin:koin-android-viewmodel:$koin_version"
// Koin AndroidX Experimental features
implementation "org.koin:koin-android-ext:$koin_version"

Ktor

// Koin for Ktor Kotlin
implementation "org.koin:koin-ktor:$koin_version"

Quickstart

Declare a Koin module

Write with the Koin DSL what you need to assemble:

// Given some classes 
class Controller(val service : BusinessService) 
class BusinessService() 

// just declare it 
val myModule = module { 
  single { Controller(get()) } 
  single { BusinessService() } 
}

Starting Koin

Use the startKoin() function to start Koin in your application.

In a Kotlin app:

fun main(vararg args : String) { 
  // start Koin!
  startKoin {
    // your modules
    modules(myModule)
  }
}

In an Android app:

class MyApplication : Application() {
  override fun onCreate(){
    super.onCreate()
    // start Koin!
    startKoin {
      // Android context
      androidContext(this@MyApplication)
      // modules
      modules(myModule)
    }
  } 
}

BoxResin/koin