Mastering Dependency Management & Build Systems in Kotlin Multiplatform

Why Dependency Management Matters

Poorly managed dependencies lead to:

• Version Conflicts: Mismatched libraries causing runtime crashes.
• Slow Builds: Unoptimized configurations wasting development time.
• Scalability Issues: Difficulty adding new features or platforms.

KMP Advantages:

• Unified Codebase: Share 70%+ code across platforms.
• Centralized Control: Manage dependencies in one place.

---

1. Dependency Management Best Practices

1.1 Centralize Library Versions

Step 1: Declare versions in gradle.properties:

# gradle.properties  
kotlinVersion = 1.9.20  
ktorVersion = 2.3.6  

Step 2: Reference in build.gradle.kts:

dependencies {  
    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:$kotlinVersion")  
    implementation("io.ktor:ktor-client-core:$ktorVersion")  
}  

Benefits:

• Avoid duplication
• Simplify updates

---

1.2 Platform-Specific Dependencies

Module	Dependency	Purpose
commonMain	kotlinx-datetime	Cross-platform date handling
androidMain	androidx.lifecycle:lifecycle-viewmodel	Android-specific UI logic
iosMain	ktor-client-darwin	iOS networking

Implementation:

// build.gradle.kts  
kotlin {  
    sourceSets {  
        val commonMain by getting {  
            dependencies {  
                implementation("org.jetbrains.kotlinx:kotlinx-datetime:0.5.0")  
            }  
        }  
        val androidMain by getting {  
            dependencies {  
                implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:2.7.0")  
            }  
        }  
    }  
}  

---

2. Configuring Multiplatform Builds

2.1 Target Platform Setup

kotlin {  
    androidTarget()  // Android  
    iosX64()         // Intel Mac iOS Simulator  
    iosArm64()       // M1/M2 iOS Devices  
    jvm("desktop") { // Desktop (Windows/macOS/Linux)  
        compilations.all {  
            kotlinOptions.jvmTarget = "17"  
        }  
    }  
    js(IR) {         // Web  
        browser()  
    }  
}  

2.2 Platform-Specific Code with expect/actual

Shared Code (commonMain)

expect fun getDeviceId(): String  

Android Implementation

actual fun getDeviceId(): String =  
    Settings.Secure.getString(context.contentResolver, Settings.Secure.ANDROID_ID)  

iOS Implementation

actual fun getDeviceId(): String =  
    UIDevice.current.identifierForVendor?.uuidString ?: ""  

---

3. Build Variants & Environment Configs

3.1 Android Product Flavors

Define in build.gradle.kts:

android {  
    flavorDimensions += "environment"  
    productFlavors {  
        create("dev") {  
            dimension = "environment"  
            buildConfigField("String", "API_URL", "\"https://dev.api.com\"")  
        }  
        create("prod") {  
            dimension = "environment"  
            buildConfigField("String", "API_URL", "\"https://api.com\"")  
        }  
    }  
}  

Access in Code:

val apiUrl = BuildConfig.API_URL  

3.2 iOS Configuration via Xcode Schemes

1. Create Dev/Prod schemes in Xcode.
2. Add API_URL to Info.plist:

<key>API_URL</key>  
<string>$(API_BASE_URL)</string>  

3. Set environment variables per scheme.

---

4. Build Speed Optimization

4.1 Gradle Configuration

gradle.properties:

# Parallel execution & caching  
org.gradle.parallel=true  
org.gradle.caching=true  
kotlin.incremental=true  

Enable Build Cache:

./gradlew build --build-cache  

4.2 Dependency Caching

Repository Setup:

dependencyResolutionManagement {  
    repositories {  
        mavenCentral()  
        google()  
    }  
}  

Estimated Impact:

Optimization	Build Time Reduction
Parallel Execution	30-40%
Incremental Compilation	50-60%

---

5. CI/CD Automation

5.1 GitHub Actions Workflow

name: KMP Build Pipeline  
on: [push]  

jobs:  
  build:  
    runs-on: ubuntu-latest  
    steps:  
      - uses: actions/checkout@v4  
      - uses: actions/setup-java@v3  
        with:  
          java-version: 17  
      - run: ./gradlew build  

  ios:  
    runs-on: macos-latest  
    needs: build  
    steps:  
      - uses: actions/checkout@v4  
      - run: ./gradlew :shared:linkDebugFrameworkIosArm64  

---

6. Troubleshooting Common Issues

6.1 Dependency Conflicts

Force a Specific Version:

dependencies {  
    implementation("io.ktor:ktor-client-core") {  
        version { strictly("2.3.6") }  
    }  
}  

Analyze Dependencies:

./gradlew :shared:dependencies > deps.txt  

6.2 Cache Corruption

Clean Gradle Cache:

./gradlew cleanBuildCache  
rm -rf ~/.gradle/caches  

---

Key Takeaways

1. Centralize Versions: Use gradle.properties for consistency.
2. Modularize Code: Split into commonMain, androidMain, iosMain.
3. Optimize Builds: Enable caching and parallel execution.
4. Automate CI/CD: Use GitHub Actions for cross-platform builds.
5. Handle Conflicts: Use strictly() and dependency reports.

By implementing these strategies, you’ll reduce build times by 40-60% and ensure seamless cross-platform development. For advanced techniques, explore the official Kotlin Multiplatform docs. 🚀

Internal Links

• A Comprehensive Guide to Cross-Platform Development
• How to Switch Ruby Versions on Mac (M1, M2, M3, M4 Guide)
• Mastering Lifecycle & Performance in Compose Multiplatform | Cross-Platform Optimization Guide

External Links

• Gradle Docs
• Kotlin Multiplatform Samples.