How do I add a watchOS target to my existing KMM project?

Question

I have a project that I made using KMM plugin on android studio for Android and iOS. The project seems to be running fine.

Now I want to add a watchOS target to the existing ios App and have no clue how to go about this.

My shared build.gradle.kts file

import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinNativeTarget

plugins {
    kotlin("multiplatform")
    kotlin("plugin.serialization")
    id("com.android.library")

    id("com.squareup.sqldelight")
}
android {
    compileSdkVersion(30)
    sourceSets["main"].manifest.srcFile("src/androidMain/AndroidManifest.xml")
    defaultConfig {
        minSdkVersion(21)
        targetSdkVersion(30)
    }
    configurations {
        create("androidTestApi")
        create("androidTestDebugApi")
        create("androidTestReleaseApi")
        create("testApi")
        create("testDebugApi")
        create("testReleaseApi")
    }
}


kotlin {
    android()

    val iosTarget: (String, KotlinNativeTarget.() -> Unit) -> KotlinNativeTarget =
        if (System.getenv("SDK_NAME")?.startsWith("iphoneos") == true)
            ::iosArm64
        else
            ::iosX64

    iosTarget("ios") {
        binaries {
            framework {
                baseName = "shared"
            }
        }
    }

    val ktorVersion = "1.4.1"
    val serializationVersion = "1.0.0-RC"
    val sqlDelightVersion: String by project
    val coroutinesVersion = "1.3.9-native-mt"


    sourceSets {
        val commonMain by getting {
            dependencies {
                implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutinesVersion")
                implementation("io.ktor:ktor-client-core:$ktorVersion")
                implementation("org.jetbrains.kotlinx:kotlinx-serialization-core:$serializationVersion")
                implementation("io.ktor:ktor-client-serialization:$ktorVersion")
                implementation("com.squareup.sqldelight:runtime:$sqlDelightVersion")
                implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.1.0")

            }
        }
        val commonTest by getting {
            dependencies {
                implementation(kotlin("test-common"))
                implementation(kotlin("test-annotations-common"))
            }
        }
        val androidMain by getting {
            dependencies {
                implementation("io.ktor:ktor-client-android:$ktorVersion")
                implementation("com.squareup.sqldelight:android-driver:$sqlDelightVersion")
            }
        }

        val androidTest by getting {
            dependencies {
                implementation(kotlin("test-junit"))
                implementation("junit:junit:4.13.2")
            }
        }
        val iosMain by getting {
            dependencies {
                implementation("io.ktor:ktor-client-ios:$ktorVersion")
                implementation("com.squareup.sqldelight:native-driver:$sqlDelightVersion")
            }
        }
        val iosTest by getting
    }
}

sqldelight {
    database("AppDatabase") {
        packageName = "com.elixer.paws.shared.cache"
    }
}


val packForXcode by tasks.creating(Sync::class) {
    val mode = System.getenv("CONFIGURATION") ?: "DEBUG"
    val framework = kotlin.targets.getByName<KotlinNativeTarget>("ios").binaries.getFramework(mode)
    val targetDir = File(buildDir, "xcode-frameworks")

    group = "build"
    dependsOn(framework.linkTask)
    inputs.property("mode", mode)

    from({ framework.outputDirectory })
    into(targetDir)
}

tasks.getByName("build").dependsOn(packForXcode)

Up until now, I just tried to open the ios app in Xcode and creating a new "watchOS" target. This sets up the watch OS app and I am able to share code between the iOS and watchOS but unable to "import shared" and all common files into watch OS. I get this error when I try to run the project on watchOs

Building for watchOS Simulator, but the linked framework 'shared.framework' was built for iOS Simulator. kotlin project

Thanks for any help. I am not very good with gradle or ios dev. Anything will help at this point.

Answer 1

You need to add a watchOS target in your build.gradle.kts similarly how the iOS target is specified:

iosTarget("ios") {
        ...
    }
watchos()

Also, if you'd like to share some of the implementation in your multiplatform code between the apple targets you may want to use dependsOn, for more information:

• Documentation
• Example