BuildKonfig

BuildConfig for Kotlin Multiplatform Project.
It currently supports embedding values from gradle file.

Table Of Contents

• Motivation
• Usage
  • Requirements
  • Gradle Configuration
  • Product Flavor?
  • Overwriting Values
• Supported Types
• Try out the sample

Motivation

Passing values from Android/iOS or any other platform code should work, but it's a hassle.
Setting up Android to read values from properties and add those into BuildConfig, and do the equivalent in iOS?
Rather I'd like to do it once.

Usage

Requirements

• Kotlin 1.5.30 or later
• Kotlin Multiplatform Project
• Gradle 7 or later

Gradle Configuration

Simple configuration

Groovy DSL

buildScript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.30'
        classpath 'com.codingfeline.buildkonfig:buildkonfig-gradle-plugin:latest_version'
    }
}

apply plugin: 'org.jetbrains.kotlin.multiplatform'
apply plugin: 'com.codingfeline.buildkonfig'
kotlin {
    // your target config...
    android()
    iosX64('ios')
}
buildkonfig {
    packageName = 'com.example.app'
    // objectName = 'YourAwesomeConfig'
    // exposeObjectWithName = 'YourAwesomePublicConfig'
defaultConfigs {
    buildConfigField 'STRING', 'name', 'value'
}
}

Kotlin DSL

import com.codingfeline.buildkonfig.compiler.FieldSpec.Type.STRING

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.30")
        classpath("com.codingfeline.buildkonfig:buildkonfig-gradle-plugin:latest_version")
    }
}
plugins {
    kotlin("multiplatform")
    id("com.codingfeline.buildkonfig")
}
kotlin {
    // your target config...
    android()
    iosX64('ios')
}
buildkonfig {
    packageName = "com.example.app"
    // objectName = "YourAwesomeConfig"
    // exposeObjectWithName = "YourAwesomePublicConfig"
defaultConfigs {
    buildConfigField(STRING, "name", "value")
}
}

• packageName

  Set the package name where BuildKonfig is being placed. Required.

• objectName

  Set the name of the generated object. Defaults to

  BuildKonfig

  .

• exposeObjectWithName

  Set the name of the generated object, and make it public.

• defaultConfigs

  Set values which you want to have in common. Required.

To generate BuildKonfig files, run

generateBuildKonfig

Above configuration will generate following simple object.

// commonMain
package com.example.app

internal object BuildKonfig {
    val name: String = "value"
}

Configuring

target

dependent values

If you want to change value depending on your targets, you can use

targetConfigs

Groovy DSL

buildScript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.30'
        classpath 'com.codingfeline.buildkonfig:buildkonfig-gradle-plugin:latest_version'
    }
}

apply plugin: 'org.jetbrains.kotlin.multiplatform'
apply plugin: 'com.codingfeline.buildkonfig'
kotlin {
    // your target config...
    android()
    iosX64('ios')
}
buildkonfig {
    packageName = 'com.example.app'
// default config is required
defaultConfigs {
    buildConfigField 'STRING', 'name', 'value'
    buildConfigNullableField 'STRING', 'nullableField', null
}

targetConfigs {
    // this name should be the same as target names you specified
    android {
        buildConfigField 'STRING', 'name2', 'value2'
        buildConfigNullableField 'STRING', 'nullableField', 'NonNull-value'
    }

    ios {
        buildConfigField 'STRING', 'name', 'valueForNative'
    }
}
}

Kotlin DSL

import com.codingfeline.buildkonfig.compiler.FieldSpec.Type.STRING

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.30")
        classpath("com.codingfeline.buildkonfig:buildkonfig-gradle-plugin:latest_version")
    }
}
plugins {
    kotlin("multiplatform")
    id("com.codingfeline.buildkonfig")
}
kotlin {
    // your target config...
    android()
    iosX64('ios')
}
buildkonfig {
    packageName = "com.example.app"
// default config is required
defaultConfigs {
    buildConfigField(STRING, "name", "value")
}

targetConfigs {
    // names in create should be the same as target names you specified
    create("android") {
        buildConfigField(STRING, "name2", "value2")
        buildConfigNullableField(STRING, "nullableField", "NonNull-value")
    }

    create("ios") {
        buildConfigField(STRING, "name", "valueForNative")
    }
}
}

• packageName

  Set the package name where BuildKonfig is being placed. Required.

• objectName

  Set the name of the generated object. Defaults to

  BuildKonfig

  .

• exposeObjectWithName

  Set the name of the generated object, and make it public.

• defaultConfigs

  Set values which you want to have in common. Required.

• targetConfigs

  Set target specific values as closure. You can overwrite values specified in

  defaultConfigs

  .

• buildConfigField(String type, String name, String value)

  Add new value or overwrite existing one.

• buildConfigNullableField((String type, String name, String value)

  Add new nullable value or overwrite existing one.

Above configuration will generate following codes.

// commonMain
package com.example.app

internal expect object BuildKonfig {
    val name: String
    val nullableField: String?
}

// androidMain
package com.example.app

internal actual object BuildKonfig {
    actual val name: String = "value"
    actual val nullableField: String? = "NonNull-value"
    val name2: String = "value2"
}

// iosMain
package com.example.app

internal actual object BuildKonfig {
    actual val name: String = "valueForNative"
    actual val nullableField: String? = null
}

Note about the hierarchical project structure

Kotlin 1.4.0 adds support for the hierarchical project structure, but BuildKonfig currently does not support this. You can use the hierarchical project structure, but intermediate SourceSets can only see fields defined in

defaultConfigs

Product Flavor?

Yes(sort of).
Kotlin Multiplatform Project does not support product flavor. Kotlin/Native part of the project has release/debug distinction, but it's not global.
So to mimick product flavor capability of Android, we need to provide additional property in order to determine flavors.

Specify default flavor in your

gradle.properties

# ROOT_DIR/gradle.properties
buildkonfig.flavor=dev

Groovy DSL

// ./mpp_project/build.gradle

buildkonfig {
    packageName = 'com.example.app'
// default config is required
defaultConfigs {
    buildConfigField 'STRING', 'name', 'value'
}
// flavor is passed as a first argument of defaultConfigs 
defaultConfigs("dev") {
    buildConfigField 'STRING', 'name', 'devValue'
}

targetConfigs {
    android {
        buildConfigField 'STRING', 'name2', 'value2'
    }

    ios {
        buildConfigField 'STRING', 'name', 'valueIos'
    }
}
// flavor is passed as a first argument of targetConfigs
targetConfigs("dev") {
    ios {
        buildConfigField 'STRING', 'name', 'devValueIos'
    }
}
}

Kotlin DSL

import com.codingfeline.buildkonfig.compiler.FieldSpec.Type.
import com.codingfeline.buildkonfig.gradle.TargetConfigDsl

buildkonfig {
    packageName = "com.example.app"
// default config is required
defaultConfigs {
    buildConfigField(STRING, "name", "value")
}
// flavor is passed as a first argument of defaultConfigs 
defaultConfigs("dev") {
    buildConfigField(STRING, "name", "devValue")
}

targetConfigs(closureOf<nameddomainobjectcontainer>&gt; {
    create("android") {
        buildConfigField(STRING, "name2", "value2")
    }

    create("ios") {
        buildConfigField(STRING, "name", "valueIos")
    }
})
// flavor is passed as a first argument of targetConfigs
targetConfigs("dev", closureOf<nameddomainobjectcontainer>&gt; {
    create("ios") {
        buildConfigField(STRING, "name", "devValueIos")
    }
})
}

In a development phase you can change value in

gradle.properties

$ ./gradlew build -Pbuildkonfig.flavor=release

Overwriting Values

If you configure same field across multiple defaultConfigs and targetConfigs, flavored targetConfigs is the strongest.

Lefter the stronger.

Flavored TargetConfig > TargetConfig > Flavored DefaultConfig > DefaultConfig

Supported Types

• String
• Int
• Long
• Float
• Boolean

Try out the sample

Have a look at

./sample

# Publish the latest version of the plugin to mavenLocal()
$ ./gradlew publishToMavenLocal

Try out the samples.
BuildKonfig will be generated in ./sample/build/buildkonfig
$ ./gradlew -p sample generateBuildKonfig