Kotlin Multiplatform

MediatorK is a pure KMP library — all APIs live in commonMain and work identically on JVM, Android, and iOS.

See Installation for dependency coordinates. Add to commonMain — Gradle resolves the right platform artifact automatically.

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Define everything in commonMain

All requests, handlers, and registrars go in commonMain — the same code runs on every platform:

// commonMain
data class GetProductQuery(val id: String) : Request<Product>

class GetProductHandler(private val repo: ProductRepository) : RequestHandler<GetProductQuery, Product> {
    override suspend fun handle(
        mediator: Mediator,
        requestContext: RequestContext,
        request: GetProductQuery,
    ): Product = repo.findById(request.id) ?: error("Not found")
}

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Creating the mediator

// commonMain — create once, share as singleton
val mediator: Mediator = MediatorFactory.create(
    registrars = listOf(ProductRegistrar(productRepository)),
)

On iOS, expose the mediator to Swift via a shared singleton or Koin.

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With Koin

See Koin integration for a complete setup that works across Android and iOS.

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Next

→ Spring Boot