I’m trying to write an MPP Android & iOS Kotli...

# multiplatform

[ribesg]

I’m trying to write an MPP Android & iOS Kotlin project from scratch. Do you really need to have the “main” android {…} block in the top build.gradle file? EDIT: see thread

[ribesg]

Maybe I misunderstood how this works and the root project should be basically empty

[kgonyon]

Yes, mpp requires either the com.android.library or com.android.application plugins which each require the android block. See https://kotlinlang.org/docs/reference/building-mpp-with-gradle.html#android-support for more information.

[ribesg]

The documentation provides Gradle DSL code but never states which Gradle file we’re talking about, so that does not help

[ribesg]

Right now my root project build.gradle.kts file is completely empty, it looks like it’s how it’s supposed to work

[kgonyon]

You want to place the android and MPP Gradle DSL in any submodule you want to be a mpp project. So if you have a submodule that is supposed to be your app, you would want to create a build.gradle.kts file in that submodule with the mpp plugin.

[kgonyon]

If you can post your project structure I can better help you.

[ribesg]

Ok so I found another bunch of example and now I think I understand that you’re supposed to have a root project and a subproject with kotlin-multiplatform and all your platforms. Is that correct?

[ribesg]

Why do you need a submodule? Can’t you do it all with a single Gradle project then?

[kgonyon]

You can do it in your root project. If that is what you are aiming for then you can place the needed gradle dsl in your root build.gradle.kts

[kgonyon]

buildscript {
    repositories {
        google()
        maven { url '<https://dl.bintray.com/kotlin/kotlin-eap>' }
        maven { url '<https://plugins.gradle.org/m2/>' }
        maven { url '<https://dl.bintray.com/jetbrains/kotlin-native-dependencies>' }
        mavenCentral()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.3.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "org.jetbrains.kotlin:kotlin-serialization:$kotlin_version"
    }
}

repositories {
    google()
    maven { url '<https://dl.bintray.com/kotlin/kotlin-eap>' }
    maven { url "<https://kotlin.bintray.com/kotlinx>" }
    mavenCentral()
    jcenter()
}

apply plugin: 'com.android.library'
apply plugin: 'kotlin-multiplatform'
apply plugin: 'kotlinx-serialization'
apply plugin: 'maven-publish'



android {
    compileSdkVersion 28
    defaultConfig {
        minSdkVersion 17
        targetSdkVersion 28
        versionCode 1
        versionName "0.0.1"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), '<http://proguard-rules.pro|proguard-rules.pro>'
        }
    }
}

[kgonyon]

kotlin {
    android()

    // This is for iPhone emulator
    // Switch here to iosArm64 (or iosArm32) to build library for iPhone device
    iosArm64("ios") {
        compilations.main {
            outputKinds("framework")

    }
    sourceSets {
        commonMain {
            dependencies {
                implementation "org.jetbrains.kotlin:kotlin-stdlib-common:$kotlin_version"
                implementation "org.jetbrains.kotlinx:kotlinx-serialization-runtime:$kotlin_serialization_version"
                implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$kotlin_coroutines_version"
                implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
            }
        }
        commonTest {
            dependencies {
                implementation "org.jetbrains.kotlin:kotlin-test-common:$kotlin_version"
                implementation "org.jetbrains.kotlin:kotlin-test-annotations-common:$kotlin_version"
            }
        }
        iosMain {
            dependencies {
                implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core-native:$kotlin_coroutines_version"
                implementation "org.jetbrains.kotlinx:kotlinx-serialization-runtime-native:$kotlin_serialization_version"
            }
        }
        iosTest {
        }
    }
}

[kgonyon]

That is an example from my project. That is all in the root build.gradle file.

[ribesg]

Is this project a 100% Kotlin app? I only saw example projects which were either 100% Kotlin MPP libraries or MPP Apps with the iOS side in Swift

[kgonyon]

This project is 100% Kotlin library that gets compiled and included into existing iOS app in swift and a separate android app in Kotlin.

[ribesg]

Yeah, that’s what I usually see. I don’t want to make a library (not yet and I have good examples for that), I want to make an app, written only in Kotlin

[kgonyon]

I see. I am not fully certain how you would setup the iOS app to use Kotlin. Perhaps someone else has an example of this.

[ribesg]

The closest thing to what I want that I found ios-wise is this https://github.com/JetBrains/kotlinconf-spinner/tree/master/clients/ios

[ribesg]

You can see that the XCode project contains no code

[ribesg]

My idea is to build a MPP project with the Android & common parts working together then adding iOS from there, I think I’ll need to do some custom things like in the example I just linked as the support isn’t huge yet

[ribesg]

Thanks for your help!