How to use Kotlin multiplatform sealed class in Swift

The problem

If you intend to use a sealed class from a Kotlin multiplatform module in a Swift client, you can access the information, but you won’t be able to use it as an enum in Swift. This is because the generated Swift code for a sealed class does not translate to an enum in Swift.

Indeed if you define a sealed class, such as the one shown below:

sealed class Destination(val path: String, val icon: ImageVector) { object Home : Destination("home", Icons.Rounded.Home) object Storybook : Destination("storybook", Icons.Rounded.Refresh) object Settings : Destination("settings", Icons.Rounded.Settings) }

The only possible way to instantiate a Destination in Swift is as follows:

let destination: Destination = Destination.Home()

when we want to do this :

let destination: Destination = .home

So, how to make these sealed classes more Swift-friendly?

Solution

We are going to use KSwift library, a Swift-friendly api generator for Kotlin/Native frameworks.

Add in root build.gradle

buildscript { repositories { mavenCentral() google() gradlePluginPortal() } dependencies { classpath("dev.icerock.moko:kswift-gradle-plugin:<latest>") } }

Add in project build.gradle

plugins { id("dev.icerock.moko.kswift") } kswift { install(dev.icerock.moko.kswift.plugin.feature.SealedToSwiftEnumFeature) }

Rebuild the project and the kswift library generated for us the Swift api and now we can access to the sealed class in a more Swift way :

let destination: Destination = .home