Mastering Cross-Platform Development with Kotlin Multiplatform Mobile

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Mastering Cross- Platform Development with Kotlin Multiplatform Mobile Google I/O Extended Yangon Su Thwe Thwe Tun

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I’m passionate about building mobile apps to achieve easier and better lifestyles in our everyday lives. I have been working as a mobile developer for 10 years with Android and Flutter. SU THWE THWE TUN MOBILE APPLICATION DEVELOPER @USA

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Introduction to KMM Kotlin Multiplatform Mobile (KMM) is an SDK by JetBrains. Use a single codebase for native iOS and Android applications. It can share common business logic and code. Write platform-specific code when necessary. WHAT IS KMM?

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Advantages of KMM KMM only shares business logic. Flutter and React Native use a single codebase for both UI and logic COMPARISON WITH OTHER CROSS-PLATFORM FRAMEWORKS KMM enhances development speed by sharing code between iOS and Android. BENEFITS

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KMM Cross-platform development GETTING STARTED WITH KMM

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INSTALL KMM PLUGIN Install Android Studio. 1. Open Android Studio. 2. Go to Preferences (or Settings on Windows/Linux). 3. Navigate to Plugins and search for "Kotlin Multiplatform Mobile". 4. Install the plugin and restart Android Studio. 5.

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Setting up a KMM project using Android Studio. 1. Open Android Studio. 2. Click on New Project. 3. Select Kotlin Multiplatform App from the project templates. 4. Follow the wizard to set up your project. 5. SETTING UP A KMM PROJECT IN ANDROID STUDIO.

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Architecture Overviews shared: Contains the shared code. commonMain: Shared code for both platforms. commonTest: Shared test code. androidMain: Android-specific code. iosMain: iOS-specific code. androidApp: Contains the Android-specific application code. iosApp: Contains the iOS-specific application code.

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KMM Cross-platform development WRITING SHARED CODE

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Writing Shared Code Networking / APIs call Data models Common business logic Database schema

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Example of Shared Code

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“expect” keyword: Declared in shared module to be implemented on each platform. USING “EXPECT” AND “ACTUAL” “actual” keyword: Declared in the Android and iOS modules to provide the actual implementations of the “expect”.

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Declare an “expect” class Platform.kt with a method getPlatformName().

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In these examples, the “actual” keyword is used to provide platform-specific implementations of the getPlatformName() method.

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KMM Cross-platform development NETWORKING WITH KTOR

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KTOR It is for servers and clients in connected systems using Kotlin. It allows to sharing of networking code between Android and iOS. KTOR IS A FRAMEWORK.

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Setting Up Ktor in Shared Module Open shared/build.gradle.kts and add the necessary Ktor dependencies. ADD KTOR DEPENDENCIES

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Create a new Kotlin file NetworkClient.kt in shared/src/commonMain/kotlin. Create a Network Client

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Create a new Kotlin file ApiService.kt in shared/src/commonMain/kotlin Make a Network Request

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Use the ApiService in Android Module

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Use the ApiService in iOS Module

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KMM Cross-platform development INTERFACING WITH PLATFORM-SPECIFIC APIS

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Calling Native APIs from Shared Code Using expect and actual keywords Define platform-agnostic API in shared code Provide platform-specific implementations

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Declare an expect class Camera with a method takePicture() Defining Platform-Agnostic API

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Provide an actual implementation using Android's MediaStore API Android implementation

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Provide an actual implementation using iOS-specific APIs iOS implementation

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Using Camera class in Shared code

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Keep platform-specific code minimal. BEST PRACTICES Use shared code for business logic. Ensure platform-specific implementations are isolated.

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KMM Cross-platform development TESTING IN KMM

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Unit tests are written in the commonTest which can be executed on both Android and iOS. Writing Unit Tests for Shared Code

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Build Configuration (shared/build.gradle.kts) Configuring Gradle for Testing

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Open Android Studio. 1. Navigate to the commonTest directory. 2. Right-click on the test file (CalculatorTest.kt). 3. Select "Run 'CalculatorTest'". 4. Running Tests on Android Studio

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Open a terminal. 1. Navigate to your project directory. 2. Execute this command. 3. Running Tests on iOS ./gradlew iosTest JUnit is used for writing and running tests on the JVM. It can be executed directly from Android Studio or via the command line. Running JUnit Tests ./gradlew test

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SUMMARY Run tests using Android Studio for Android and command line for iOS. Use kotlin.test for cross-platform testing. Use JUnit for JVM-specific testing. Tools and Frameworks for Testing:

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KMM Cross-platform development Effective Tools and Techniques for KMM Development

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Overview of IDE Support Full support for Kotlin Multiplatform projects. Integrated tools for coding, building, and debugging. PRIMARY IDE: ANDROID STUDIO IntelliJ IDEA Xcode (for iOS-specific development) OTHER SUPPORTED IDES

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Debugging Techniques Use Android Studio’s built-in debugger for Android Use Xcode for debugging iOS code DEBUGGING Print statements and logging for shared code Using conditional breakpoints CROSS-PLATFORM DEBUGGING

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KMM Cross-platform development Real-World Use Cases of KMM

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Case Study: Netflix - Mobile Studio Company: Netflix Project: Mobile Studio Objective: Build a mobile application for internal use by Netflix’s creative teams. Overview :

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Case Study: Netflix - Mobile Studio Frequent updates and features required for both iOS and Android. High costs and time consumption due to maintaining separate codebases. Difficulty in synchronizing new features and bug fixes across platforms. Challenges :

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Case Study: Netflix - Mobile Studio Implemented KMM to share common business logic and core functionalities. Utilized Kotlin for shared code and native Swift/Java for platform-specific implementations. Focused on sharing models, data handling, and business logic while keeping UI native. Solution :

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Case Study: Netflix - Mobile Studio Networking: Used Ktor for making network requests. Persistence: Implemented SQLDelight for shared database operations. ViewModels: Shared ViewModel logic using KMM to manage UI-related data. Technical Details :

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Case Study: Netflix - Mobile Studio Efficiency: Increased development efficiency by sharing up to 80% of the codebase. Speed: Faster feature rollouts and synchronized updates across both platforms. Consistency: Improved consistency in features and performance across platforms. Benefits :

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Case Study: Netflix - Mobile Studio Results : Increased Efficiency Shared codebase reduces duplication of effort Consistent User Experience Unified business logic across platforms ensures consistency Cost Savings Reduced development and maintenance costs

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KMM Cross-platform development Resources and Community of KMM

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Overview of the KMM Community Active Community Support Forums, Slack channels, and social media groups Official Documentation and Tutorials Comprehensive guides on the JetBrains website

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POPULAR LIBRARIES AND TOOLS Ktor For network operations SQLDelight Type-safe SQL for Kotlin Multiplatform Multiplatform Settings For managing application settings across platforms

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GitHub repositories for community- driven projects Getting involve in reporting issues, submitting PRs, writing documentation Contribution Opportunities

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IMPACT ON MOBILE DEVELOPMENT Unified Development Process Single codebase for business logic across platforms Cost and Time Efficiency Reduced development time and costs Evolving Best Practices New design patterns and practices for cross-platform development

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Conclusion Use expect and actual for platform-specific implementations Keep platform-specific code minimal and isolated Share business logic across platforms KEY TAKEAWAY

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Email address : [email protected] THANK YOU!