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Annotations for Definitions and Modules in Kotlin Multiplatform App

KSP Setup​

Please follow KSP setup as described in official documentation: KSP with Kotlin Multiplatform

You can also check the Hello Koin KMP project with basic setup for Koin Annotations.

Add the KSP Plugin

plugins {
    alias(libs.plugins.ksp)
}

Use annotations library in common API:

sourceSets {
        commonMain.dependencies {
            implementation(libs.koin.core)
            api(libs.koin.annotations)
            // ...
        }
}

And don't forget to configure KSP on right sourceSet:

dependencies {
    add("kspCommonMainMetadata", libs.koin.ksp.compiler)
    add("kspAndroid", libs.koin.ksp.compiler)
    add("kspIosX64", libs.koin.ksp.compiler)
    add("kspIosArm64", libs.koin.ksp.compiler)
    add("kspIosSimulatorArm64", libs.koin.ksp.compiler)
}

Declaring Common Modules & KMP Expect Components​

In your commonMain sourceSet, you just need to declare a Module to scan the package that will have native implementations of your expect class or function.

Below we have a PlatformModule, scanning in com.jetbrains.kmpapp.platform package where we have PlatformHelper expect class. The module class is annotated with @Module and @ComponentScan annotations. 

// in commonMain

@Module
@ComponentScan("com.jetbrains.kmpapp.platform")
class PlatformModule

// package com.jetbrains.kmpapp.platform 

expect class PlatformHelper {
    fun getName() : String
}
note

The generated code is done in each platform implementation. Module package scanning will gather the right platform implementation.

Annotate Native Components​

In each implementation sourceSet, you can now define the right platform implementation. Those implementation are annotated with @Single (could be anotehr definition annotation):

// in androidMain
// package com.jetbrains.kmpapp.platform

@Single
actual class PlatformHelper(
    val context: Context
){
    actual fun getName(): String = "I'm Android - $context"
}

// in nativeMain
// package com.jetbrains.kmpapp.platform

@Single
actual class PlatformHelper(){
    actual fun getName(): String = "I'm Native"
}