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Kotlin Multiplatform Overview

Anchor DI is multiplatform by design. It runs on Android, iOS, Desktop (JVM), and Web (Wasm). Generated code lives in commonMain; platform-specific dependencies use expect / actual. This page explains how Anchor DI fits into a KMP project and what you need to know about source sets and KSP targets.

What is Kotlin Multiplatform?​

Kotlin Multiplatform (KMP) lets you share code across platforms — Android, iOS, Desktop, Web — while keeping platform-specific code where it belongs. You write business logic (networking, data layer, use cases) once in Kotlin and run it everywhere. Anchor DI is built for this: the same annotations, the same API, the same mental model on all platforms.

Source Sets​

In KMP, source sets define where code lives and which platforms it targets. Anchor DI uses the same structure:

Source SetUse
commonMainShared DI graph, modules, @Inject classes. Your main DI setup lives here.
androidMainAndroid-specific modules (e.g. ActivityScope), platform providers.
iosArm64Main / iosSimulatorArm64MainiOS getAnchorContributors() actual. KSP generates into target-specific dirs; you need actuals here, not iosMain.
jvmMainDesktop/JVM-specific if needed (e.g. JVM-only modules).
wasmJsMainWeb/Wasm-specific if needed.

Important for iOS: KSP generates code into iosArm64Main and iosSimulatorArm64Main, not iosMain. So you need an actual for getAnchorContributors() in both iosArm64Main and iosSimulatorArm64Main. See Platform-Specific Setup.

KSP Targets​

Anchor DI uses KSP (Kotlin Symbol Processing) to generate code at compile time. You must add the KSP processor for each Kotlin target you use:

dependencies {
    add("kspCommonMainMetadata", "io.github.12345debdut:anchor-di-ksp:x.x.x")
    add("kspAndroid", "io.github.12345debdut:anchor-di-ksp:x.x.x")
    add("kspIosArm64", "io.github.12345debdut:anchor-di-ksp:x.x.x")
    add("kspIosSimulatorArm64", "io.github.12345debdut:anchor-di-ksp:x.x.x")
    add("kspJvm", "io.github.12345debdut:anchor-di-ksp:x.x.x")
    add("kspWasmJs", "io.github.12345debdut:anchor-di-ksp:x.x.x")
}
  • kspCommonMainMetadata — For shared code. Required if you have commonMain and use KSP there.
  • kspAndroid — For Android target.
  • kspIosArm64 / kspIosSimulatorArm64 — For iOS device and simulator.
  • kspJvm — For JVM/Desktop target.
  • kspWasmJs — For Web/Wasm target.

Add KSP only for the targets you actually use.

Platform-Specific Dependencies​

When you need platform-specific types (e.g. Context on Android, UIApplication on iOS), use expect / actual:

// commonMain — expect
expect class PlatformContext

// androidMain — actual
actual class PlatformContext(private val context: Context)

// iosMain (or iosArm64Main / iosSimulatorArm64Main) — actual
actual class PlatformContext(private val application: UIApplication)

Then provide them via a module with platform-specific sources:

@Module
@InstallIn(SingletonComponent::class)
object PlatformModule {
    @Provides
    @Singleton
    fun providePlatformContext(): PlatformContext = PlatformContext(/* platform-specific */)
}

Each platform has its own PlatformModule that provides the platform-specific PlatformContext. The shared code depends only on the PlatformContext interface; it doesn't know about Context or UIApplication.

Next Steps​