Multiplatform programming

Support for multiplatform programming is one of Kotlin’s key benefits. It reduces time spent writing and maintaining the same code for different platforms while retaining the flexibility and benefits of native programming.

This is how Kotlin Multiplatform works.

• Common Kotlin includes the language, core libraries, and basic tools. Code written in common Kotlin works everywhere on all platforms.

• With Kotlin Multiplatform libraries, you can reuse the multiplatform logic in common and platform-specific code. Common code can rely on a set of libraries that cover everyday tasks such as HTTP, serialization, and managing coroutines.

• To interop with platforms, use platform-specific versions of Kotlin. Platform-specific versions of Kotlin (Kotlin/JVM, Kotlin/JS, Kotlin/Native) include extensions to the Kotlin language, and platform-specific libraries and tools.

• Through these platforms you can access the platform native code (JVM, JS, and Native) and leverage all native capabilities.

With Kotlin Multiplatform, spend less time on writing and maintaining the same code for different platforms – just share it using the mechanisms Kotlin provides:

• Share code among all platforms used in your project. Use it for sharing the common business logic that applies to all platforms.

  

• Share code among some platforms included in your project but not all. Do this when you can reuse much of the code in similar platforms.

  

  

If you need to access platform-specific APIs from the shared code, use the Kotlin mechanism of expected and actual declarations.

With this mechanism, a common source set defines an expected declaration, and platform source sets must provide the actual declaration that corresponds to the expected declaration. This works for most Kotlin declarations, such as functions, classes, interfaces, enumerations, properties, and annotations.

//Common expect fun randomUUID(): String 

//Android import java.util.* actual fun randomUUID() = UUID.randomUUID().toString() 

//iOS import platform.Foundation.NSUUID actual fun randomUUID(): String = NSUUID().UUIDString()