Create the project from a template

1. In Android Studio, select File | New | New Project.

2. Select Kotlin Multiplatform App in the list of project templates, and click Next.

   

3. Specify a name for your first application, and click Next.

   

4. In the iOS framework distribution list, select the Regular framework option.

   

5. Keep the default names for the application and shared folders. Click Finish.

The project will be set up automatically. It may take some time to download and set up the required components when you do this for the first time.

Examine the project structure

To view the full structure of your mobile multiplatform project, switch the view from Android to Project.

Each Kotlin Multiplatform Mobile project includes three modules:

• shared is a Kotlin module that contains the logic common for both Android and iOS applications – the code you share between platforms. It uses Gradle as the build system that helps you automate your build process. The shared module builds into an Android library and an iOS framework.

• androidApp is a Kotlin module that builds into an Android application. It uses Gradle as the build system. The androidApp module depends on and uses the shared module as a regular Android library.

• iOSApp is an Xcode project that builds into an iOS application. It depends on and uses the shared module as an iOS framework. The shared module can be used as a regular framework or as a CocoaPods dependency, based on what you've chosen in the previous step in iOS framework distribution. In this tutorial, it's a regular framework dependency.

The shared module consists of three source sets: androidMain, commonMain, and iosMain. Source set is a Gradle concept for a number of files logically grouped together where each group has its own dependencies. In Kotlin Multiplatform, different source sets in a shared module can target different platforms.

Run your application

You can run your multiplatform application on Android or iOS.

Update your application

1. Open the Greeting.kt file in shared/src/commonMain/kotlin. This directory stores the shared code for both Android and iOS. If you make changes to the shared code, you will see them reflected in both applications.

   

2. Update the shared code by using reversed(), the Kotlin standard library function for reversing text that works on all platforms:

   class Greeting {
       private val platform: Platform = getPlatform()
   
       fun greeting(): String {
           return "Guess what it is! > ${platform.name.reversed()}!"
       }
   }
   

3. Run the updated application on Android.

   

4. Run the updated application on iOS.

   

Next step

Learn about dependencies and add a third-party library to your project to expand its functionality.

Get help

• Kotlin Slack. Get an invite and join the #multiplatform channel.

• Kotlin issue tracker. Report a new issue.