Compose Multiplatform Tools: Streamlining Jetpack Compose Development

Jetpack Compose has revolutionized Android UI development with its declarative approach and Kotlin-based syntax. Expanding beyond Android, Compose Multiplatform (CMP) allows developers to build applications that share a significant amount of code across multiple platforms, including Android, iOS, desktop (JVM), and web. To efficiently manage and develop such projects, robust tooling is essential. In this article, we will delve into the various Compose Multiplatform development tools that empower developers to streamline their workflow.

What is Compose Multiplatform?

Compose Multiplatform is a declarative UI framework that lets you write UI code once and deploy it across various platforms. It’s built upon Kotlin Multiplatform, leveraging the power of Kotlin to share business logic and UI layers between different operating systems and devices. CMP aims to reduce development time and effort by maximizing code reuse while providing native-like performance and look on each target platform.

Why Use Compose Multiplatform?

• Code Sharing: Maximize code reuse across multiple platforms, reducing development effort.
• Native Performance: CMP provides a native-like experience on each platform by leveraging platform-specific APIs.
• Modern UI Framework: Embraces declarative UI, making UI development more intuitive and maintainable.
• Unified Ecosystem: Powered by Kotlin, simplifying development for those already familiar with Kotlin and Jetpack Compose.

Development Tools for Compose Multiplatform

To fully harness the power of Compose Multiplatform, it’s important to utilize the right set of tools. These tools can range from IDEs and SDKs to libraries and testing frameworks.

1. Integrated Development Environments (IDEs)

The primary IDE for Compose Multiplatform development is IntelliJ IDEA or Android Studio, as both offer excellent Kotlin support and essential plugins for multiplatform development.

IntelliJ IDEA / Android Studio

IntelliJ IDEA and Android Studio provide comprehensive support for Kotlin, Gradle, and Compose development, including:

• Code Completion: Enhances productivity with smart suggestions and autocompletion for Kotlin and Compose APIs.
• Debugging: Robust debugging capabilities, allowing you to step through code, set breakpoints, and inspect variables.
• Refactoring: Tools for safely renaming, moving, and restructuring code.
• Build Automation: Integration with Gradle for build automation, dependency management, and project configuration.

To set up a CMP project, you’ll need the Kotlin plugin installed and configured in your IDE.

// Example: build.gradle.kts for a CMP project
plugins {
    kotlin("multiplatform") version "1.9.0" // Ensure Kotlin plugin is enabled
    id("org.jetbrains.compose") version "1.5.1"
}

kotlin {
    jvm {
        compilations.all {
            kotlinOptions.jvmTarget = "11"
        }
        withJava()
    }
    iosX64()
    iosArm64()
    iosSimulatorArm64()

    sourceSets {
        val commonMain by getting {
            dependencies {
                implementation(compose.runtime)
                implementation(compose.foundation)
                implementation(compose.ui)
            }
        }
        val androidMain by getting {
            dependencies {
                implementation("androidx.appcompat:appcompat:1.6.1")
                implementation("androidx.core:core-ktx:1.12.0")
                implementation(compose.uiToolingPreview)
                debugImplementation(compose.uiTooling)
            }
        }
        val iosX64Main by getting
        val iosArm64Main by getting
        val iosSimulatorArm64Main by getting
        val iosMain by getting {
            dependsOn(commonMain)
        }
        val jvmMain by getting {
            dependencies {
                implementation(compose.desktop.ui)
            }
        }
    }
}

compose {
    desktop {
        application {
            mainClass.set("MainKt")
            nativeDistributions {
                targetFormats(org.jetbrains.compose.desktop.application.dsl.TargetFormat.Dmg, org.jetbrains.compose.desktop.application.dsl.TargetFormat.Msi, org.jetbrains.compose.desktop.application.dsl.TargetFormat.Deb)
                packageName = "YourAppPackageName"
                packageVersion = "1.0.0"
            }
        }
    }
}

android {
    namespace = "your.application.namespace"
    compileSdk = 34

    defaultConfig {
        applicationId = "your.application.id"
        minSdk = 24
        targetSdk = 34
        versionCode = 1
        versionName = "1.0"
    }
    buildFeatures {
        compose = true
    }
    composeOptions {
        kotlinCompilerExtensionVersion = "1.5.1"
    }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_1_8
        targetCompatibility = JavaVersion.VERSION_1_8
    }
}

2. Kotlin Multiplatform Libraries

Kotlin Multiplatform Libraries help share code across different platforms. Common libraries include:

• Kotlin Standard Library (stdlib): Provides common functionalities, such as collections, IO, and basic utilities.
• Kotlinx Serialization: Handles object serialization to various formats like JSON.
• Ktor: A framework for building asynchronous clients and servers, ideal for handling network requests across platforms.
• SQLDelight: Generates typesafe Kotlin APIs from SQL schemas, useful for database management.

Example: Using Ktor for Making Network Requests

import io.ktor.client.*
import io.ktor.client.request.*
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.launch

expect val platform: String

fun hello(): String = "Hello from $platform"

fun makeApiCall() {
    GlobalScope.launch {
        val client = HttpClient()
        val result: String = try {
            client.get("https://ktor.io/").status.toString()
        } catch (e: Exception) {
            "Request failed: ${e.message}"
        }
        println("API Result: $result")
        client.close()
    }
}

fun main() {
    println(hello())
    makeApiCall()
}

With Ktor, you can define API calls in the common module and implement platform-specific behavior only where necessary.

3. Compose UI Preview Tools

The Compose UI preview tools in Android Studio are valuable for CMP projects to visualize UI components quickly without deploying to actual devices or emulators.

import androidx.compose.desktop.ui.tooling.preview.Preview
import androidx.compose.material.Text
import androidx.compose.runtime.Composable

@Composable
fun Greeting(name: String) {
    Text(text = "Hello $name!")
}

@Preview
@Composable
fun DefaultPreview() {
    Greeting("Compose Multiplatform")
}

The @Preview annotation allows you to see a live rendering of your composable in the IDE.

4. Testing Frameworks

Testing is crucial in CMP projects to ensure code works correctly on all target platforms. Common testing frameworks include:

• JUnit: Used for JVM-based unit tests.
• Kotlinx Test: Provides common testing APIs across multiple platforms.
• Espresso: For Android UI testing.
• XCTest: For iOS unit testing (through Kotlin/Native).

Example: Using JUnit for JVM tests

import org.junit.Test
import kotlin.test.assertEquals

class CommonTest {
    @Test
    fun testHello() {
        assertEquals("Hello from JVM", hello())
    }
}

Platform-specific test implementations might be needed for UI components.

5. Build Tools

Gradle is the standard build tool for Kotlin Multiplatform projects. It handles dependency management, build configuration, and packaging for different platforms.

// Example Gradle configuration snippet

kotlin {
    jvm()
    android {
        publishLibraryVariants("release", "debug")
    }
    iosX64()
    iosArm64()
    iosSimulatorArm64()
    
    sourceSets {
        commonMain {
            dependencies {
                implementation("org.jetbrains.kotlin:kotlin-stdlib-common")
            }
        }
        androidMain {
            dependencies {
                implementation("androidx.appcompat:appcompat:1.6.1")
            }
        }
        iosX64Main { dependsOn(commonMain) }
        iosArm64Main { dependsOn(commonMain) }
        iosSimulatorArm64Main { dependsOn(commonMain) }
    }
}

Gradle allows you to configure build tasks for each platform separately, facilitating seamless integration and packaging.

6. Continuous Integration/Continuous Deployment (CI/CD) Tools

CI/CD tools like Jenkins, GitLab CI, and GitHub Actions are indispensable for automating builds, tests, and deployments in CMP projects.

# Example GitHub Actions workflow for a CMP project
name: CMP Build and Test

on:
  push:
    branches: [ "main" ]
  pull_request:
    branches: [ "main" ]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Set up JDK 11
        uses: actions/setup-java@v3
        with:
          java-version: '11'
          distribution: 'temurin'
      - name: Grant execute permission for gradlew
        run: chmod +x gradlew
      - name: Build with Gradle
        run: ./gradlew build

Automating the build and testing process helps catch issues early and ensures that your CMP application remains stable and reliable across all platforms.

Conclusion

Compose Multiplatform offers a powerful way to build cross-platform applications with shared UI code. By utilizing the right development tools, including robust IDEs, Kotlin Multiplatform Libraries, Compose UI preview tools, comprehensive testing frameworks, build automation tools, and CI/CD pipelines, developers can significantly streamline their workflow, reduce development time, and ensure the quality and reliability of their applications on every target platform. Embrace these tools to unlock the full potential of Compose Multiplatform.