Kotlin Multiplatform Mobile (KMM) is a cutting-edge technology developed by JetBrains, designed to simplify mobile app development by allowing you to share code across Android and iOS platforms. KMM leverages the power of Kotlin, a versatile and expressive programming language, to create a shared codebase, reducing development effort, minimizing code duplication, and ensuring consistent functionality across both major mobile platforms.

Why Use Kotlin Multiplatform Mobile?

Kotlin Multiplatform Mobile offers a range of compelling benefits:

• Code Reusability: Write business logic, data models, and other core code once, and use it on both Android and iOS platforms, reducing redundancy.
• Consistency: Shared code ensures that the app behaves consistently across platforms, providing a seamless user experience.
• Efficiency: Save development time by maintaining a single codebase and reducing the need for platform-specific code.

Setting Up a Kotlin Multiplatform Mobile Project

To get started with Kotlin Multiplatform Mobile, follow these steps:

1. Install Kotlin: Ensure that you have Kotlin and a compatible development environment installed.
2. Create a Shared Module: Start by creating a shared module within your project. This module contains the code shared between Android and iOS.

Shared Code Example

Here’s an example of a simple shared code module for a Kotlin Multiplatform Mobile project:

// SharedCode.kt

class SharedClass {
    fun sharedFunction(): String {
        return "Hello from shared code!"
    }
}

This code can be used on both Android and iOS platforms, eliminating the need for duplicate implementations.

Platform-Specific Modules

For platform-specific code or user interface elements, you can create platform-specific modules. Each module has its own implementation but can utilize the shared code from the shared module. For instance, you might have an Android module and an iOS module in your Kotlin Multiplatform Mobile project, each with its own platform-specific code and UI components.

Building and Running a Kotlin Multiplatform Mobile Project

To build and run your Kotlin Multiplatform Mobile project, you can use the following commands in the respective platform modules:

For Android:

./gradlew :shared:build
./gradlew :androidApp:installDebug

For iOS (using Kotlin Native):

./gradlew :shared:build
./gradlew :iosApp:run

These commands build the shared code and the platform-specific modules, allowing you to run your Kotlin Multiplatform Mobile project on Android and iOS platforms.

Kotlin Multiplatform Mobile Libraries

Kotlin Multiplatform Mobile also supports the creation of shared libraries that can be used in multiple projects. These libraries can include data models, network communication, and other common functionality. To create a shared library, you can use the following command:

./gradlew :sharedLibrary:build

This command builds the Kotlin Multiplatform library, which can be imported into various projects to reuse shared code and functionality.

Conclusion

Kotlin Multiplatform Mobile is a revolutionary technology that simplifies cross-platform mobile app development. By creating a shared codebase, you can efficiently develop applications for Android and iOS, reduce code duplication, and ensure consistent behavior across platforms. This guide introduced the fundamentals of KMM, shared code examples, building and running a project, and the concept of shared libraries.