Compose Multiplatform: Guide to App Distribution in Jetpack Compose

Kotlin Multiplatform (KMP) has revolutionized the way developers approach cross-platform app development, and Jetpack Compose has quickly become the go-to UI toolkit for Android. Combining the power of KMP and Jetpack Compose allows you to write UI code once and deploy it across multiple platforms, including Android, iOS, desktop, and web. However, distributing a Compose Multiplatform app requires a specific set of steps and considerations. This article will guide you through the process of distributing your Compose Multiplatform application using Jetpack Compose.

What is Compose Multiplatform?

Compose Multiplatform is a declarative UI framework powered by Kotlin and JetBrains. It allows you to build native desktop, web, Android, and iOS applications from a single codebase. By using Compose Multiplatform, you can share a significant portion of your application logic and UI code, reducing development time and improving code maintainability.

Why Use Compose Multiplatform?

• Code Sharing: Write once, deploy everywhere, reducing codebase duplication.
• Native Performance: Achieve native-like performance on each platform.
• Modern UI: Utilize Jetpack Compose’s modern declarative UI paradigm.
• Multi-Platform Support: Target Android, iOS, desktop, and web with a single project.

Setting Up a Compose Multiplatform Project

Before diving into distribution, you need to have a Compose Multiplatform project set up. You can easily create one using the Kotlin Multiplatform wizard in IntelliJ IDEA or Android Studio.

Step 1: Create a New Project

• Open IntelliJ IDEA or Android Studio.
• Select “New Project” and choose “Kotlin Multiplatform App.”
• Configure the project name, location, and target platforms (Android, iOS, Desktop, Web).
• Follow the wizard instructions to set up your project.

Step 2: Project Structure

A typical Compose Multiplatform project structure looks like this:

MyComposeApp/
├── androidApp/        # Android-specific code
├── iosApp/            # iOS-specific code
├── desktopApp/        # Desktop-specific code
├── jsApp/             # Web-specific code (Kotlin/JS)
├── shared/           # Shared Kotlin code (business logic, UI components)
│   ├── src/commonMain/     # Common code for all platforms
│   ├── src/androidMain/    # Android-specific implementations
│   ├── src/iosMain/        # iOS-specific implementations
│   ├── src/jvmMain/        # Desktop-specific implementations
│   └── src/jsMain/         # Web-specific implementations
├── build.gradle.kts   # Project-level Gradle configuration
└── settings.gradle.kts# Settings file for Gradle

Distributing Compose Multiplatform Apps

Distributing a Compose Multiplatform app varies based on the target platform. Below are the steps for each platform:

1. Distributing the Android App

Distributing the Android app is similar to distributing a standard Android application. Follow these steps:

Step 1: Configure Build Variants

In your androidApp/build.gradle.kts file, configure the release build variant:

android {
    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile("proguard-android-optimize.txt"), "proguard-rules.pro"
            signingConfig signingConfigs.release
        }
    }
    signingConfigs {
        create("release") {
            storeFile = file("path/to/your/keystore.jks")
            storePassword = "your_store_password"
            keyAlias = "your_key_alias"
            keyPassword = "your_key_password"
        }
    }
}

Step 2: Build the APK or AAB

Generate a signed APK or AAB (Android App Bundle) using Gradle:

./gradlew assembleRelease
# or
./gradlew bundleRelease

Step 3: Distribute Through Google Play Store

Upload the generated APK or AAB to the Google Play Store for distribution to Android users.

2. Distributing the iOS App

Distributing the iOS app involves creating an IPA (iOS App Archive) and using Xcode to deploy the application. Here are the steps:

Step 1: Configure Signing and Capabilities

Open the iOS project in Xcode (located in the iosApp directory). Configure the signing and capabilities:

• Set up a signing certificate and provisioning profile in Xcode.
• Configure necessary app capabilities (e.g., push notifications, location services).

Step 2: Build for Release

Build the project for release in Xcode. Select “Generic iOS Device” as the target.

Step 3: Archive the App

Archive the app to create an IPA file. Go to “Product” -> “Archive.”

Step 4: Distribute Through App Store Connect

Upload the IPA file to App Store Connect (appstoreconnect.apple.com) for distribution through the Apple App Store or TestFlight.

3. Distributing the Desktop App

Distributing the desktop app requires packaging the application into an executable format specific to the target operating system (Windows, macOS, Linux).

Step 1: Configure Gradle for Desktop Packaging

In the desktopApp/build.gradle.kts, configure the packaging task using plugins like jpackage.

plugins {
    id("org.jetbrains.compose") version "1.6.0" // Ensure you use the latest version
    application
}

group = "org.example"
version = "1.0-SNAPSHOT"

kotlin {
    jvmToolchain(11)
}

dependencies {
    implementation(compose.desktop.currentOs)
    // Other dependencies
}

compose {
    desktop {
        application {
            mainClass = "MainKt" // Replace with your main class
            applicationName = "MyDesktopApp"

            // Define packaging options
            packageOptions {
                imagePath = listOf("icons/app-icon.png") // App icon
                packageName = "com.example.mydesktopapp"
                packageVersion = "1.0.0"
            }

            // Define platform-specific options
            windows {
                installerOptions {
                    upgradeUuid = "your-unique-upgrade-uuid"
                }
            }
        }
    }
}

Step 2: Build the Desktop Package

Use the Gradle task to build the desktop package:

./gradlew packageRelease

Step 3: Distribute the Executable

Distribute the generated executable (e.g., .exe for Windows, .dmg for macOS, .deb or .rpm for Linux) to desktop users.

4. Distributing the Web App

Distributing the web app involves compiling the Kotlin/JS code to JavaScript and deploying it to a web server.

Step 1: Configure Gradle for Web Distribution

In the jsApp/build.gradle.kts file, configure the compilation and bundling process:

plugins {
    id("org.jetbrains.kotlin.js") version "1.9.22"
    id("org.jetbrains.compose") version "1.6.0"
}

group = "org.example"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

kotlin {
    js(IR) {
        browser {
            commonWebpackConfig {
                cssSupport.enabled = true
            }
            webpackTask {
                outputFileName = "MyWebApp.js"
            }
        }
        binaries.executable()
    }
}

dependencies {
    implementation(compose.html.core)
    // Other dependencies
}

Step 2: Build the Web App

Use Gradle to build the web app:

./gradlew jsBrowserProductionWebpack

Step 3: Deploy to a Web Server

Deploy the generated JavaScript, HTML, and CSS files (usually located in the jsApp/build/distributions directory) to a web server (e.g., Apache, Nginx, Netlify, Vercel).

Best Practices for Compose Multiplatform App Distribution

• Optimize Assets: Compress images and other assets to reduce the app size and improve loading times.
• Code Obfuscation: Use code obfuscation techniques to protect your codebase from reverse engineering.
• Testing: Thoroughly test your app on all target platforms to ensure a consistent user experience.
• Automation: Automate the build and distribution process using CI/CD pipelines (e.g., Jenkins, GitHub Actions).
• Versioning: Implement a robust versioning strategy to manage updates effectively.

Conclusion

Distributing a Compose Multiplatform app involves platform-specific steps and configurations. By following the guidelines outlined in this article, you can successfully deploy your application to Android, iOS, desktop, and web platforms, leveraging the power of Kotlin Multiplatform and Jetpack Compose. Ensure you thoroughly test and optimize your app for each platform to deliver a seamless user experience.