KMPプロジェクト構造：commonMain、androidMain、iosMain

KMPとは

// Typical KMP module structure:
// shared/
//   src/
//     commonMain/kotlin/   <- shared code
//     androidMain/kotlin/  <- Android-only
//     iosMain/kotlin/      <- iOS-only
//     commonTest/kotlin/   <- shared tests
fun main() { println("KMP: one codebase, many targets") }

ソースセットの階層

// build.gradle.kts (Kotlin DSL)
kotlin {
    androidTarget()
    iosX64()
    iosArm64()
    iosSimulatorArm64()

    sourceSets {
        val commonMain by getting {
            dependencies { /* shared deps */ }
        }
        val androidMain by getting
        val iosMain by getting
    }
}

commonMain: 共有ロジック

// commonMain/kotlin/com/example/domain/User.kt
data class User(val id: String, val name: String, val email: String)

// commonMain/kotlin/com/example/repository/UserRepository.kt
interface UserRepository {
    suspend fun getUser(id: String): User?
    suspend fun saveUser(user: User)
}

androidMain: Android固有のコード

// androidMain/kotlin/com/example/platform/PlatformLogger.kt
import android.util.Log
class AndroidLogger : Logger {
    override fun log(msg: String) = Log.d("App", msg)
}
// androidMain/kotlin/com/example/di/PlatformModule.kt
// Koin or Hilt module that binds AndroidLogger to Logger

iosMain: iOS固有のコード

// iosMain/kotlin/com/example/platform/PlatformLogger.kt
import platform.Foundation.NSLog
class IosLogger : Logger {
    override fun log(msg: String) = NSLog(msg)
}
// iOS uses Kotlin/Native runtime; no JVM here

iOSターゲットのGradle設定

// build.gradle.kts
kotlin {
    iosX64()
    iosArm64()
    iosSimulatorArm64()
    sourceSets {
        val iosMain by creating {
            dependsOn(commonMain.get())
        }
        val iosX64Main by getting { dependsOn(iosMain) }
        val iosArm64Main by getting { dependsOn(iosMain) }
        val iosSimulatorArm64Main by getting { dependsOn(iosMain) }
    }
}

commonMainの共有依存関係

// commonMain dependencies example:
// implementation("io.ktor:ktor-client-core:2.3.0")
// implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.5.1")
// implementation("io.insert-koin:koin-core:3.4.0")

// androidMain:
// implementation("io.ktor:ktor-client-okhttp:2.3.0")
// iosMain:
// implementation("io.ktor:ktor-client-darwin:2.3.0")

commonTest: 共有テスト

// commonTest/kotlin/UserRepositoryTest.kt
import kotlin.test.Test
import kotlin.test.assertEquals
class UserRepositoryTest {
    @Test
    fun testUserCreation() {
        val user = User("1", "Alice", "alice@example.com")
        assertEquals("Alice", user.name)
    }
}

中間ソースセット

// Create appleMain shared between iOS and macOS:
sourceSets {
    val appleMain by creating { dependsOn(commonMain.get()) }
    val iosMain by getting { dependsOn(appleMain) }
    val macosMain by getting { dependsOn(appleMain) }
}

プロジェクトのファイル構成

// shared/
//   build.gradle.kts
//   src/
//     commonMain/kotlin/
//       domain/           User.kt, Post.kt
//       repository/       UserRepository.kt
//       usecase/          GetUserUseCase.kt
//     androidMain/kotlin/
//       repository/       RoomUserRepository.kt
//     iosMain/kotlin/
//       repository/       CoreDataUserRepository.kt
//     commonTest/kotlin/  GetUserUseCaseTest.kt

CocoaPods / SPMとの統合

// build.gradle.kts for CocoaPods:
kotlin {
    cocoapods {
        name = "Shared"
        version = "1.0"
        ios.deploymentTarget = "14.0"
        framework { baseName = "Shared" }
    }
}
// Run: ./gradlew :shared:podPublishReleaseXCFramework

確認問題

まとめ