Using Kotlin from local Swift packages

Edit pageLast modified: 03 March 2025

This is a local integration method. It can work for you if:


  • You have an iOS app with local SPM modules.

  • You've already set up a Kotlin Multiplatform project targeting iOS on your local machine.

  • Your existing iOS project has a static linking type.


Choose the integration method that suits you best

In this tutorial, you'll learn how to integrate a Kotlin framework from a Kotlin Multiplatform project into a local package using the Swift package manager (SPM).

Direct integration diagram

To set up the integration, you'll add a special script that uses the embedAndSignAppleFrameworkForXcode Gradle task as a pre-action in your project's build settings. To see the changes made in common code reflected in your Xcode project, you'll only need to rebuild the Kotlin Multiplatform project.

This way, you can easily use Kotlin code in local Swift packages, compared to a regular direct integration method, that adds the script to the build phase and requires rebuilding both the Kotlin Multiplatform and the iOS project to get the changes from the common code.

tip

If you aren't familiar with Kotlin Multiplatform, learn how to set up the environment and create a cross-platform application from scratch first.

Set up the project

The feature is available starting with Kotlin 2.0.0.

tip

To check the Kotlin version, navigate to the build.gradle(.kts) file in the root of your Kotlin Multiplatform project. You'll see the current version in the plugins {} block at the top of the file.

Alternatively, check the version catalog in the gradle/libs.versions.toml file.

The tutorial assumes that your project is using direct integration approach with the embedAndSignAppleFrameworkForXcode task in the project's build phase. If you're connecting a Kotlin framework through CocoaPods plugin or through Swift package with binaryTarget, migrate first.

Connect the framework to your project

note

The integration into swift build is currently not supported.

To be able to use Kotlin code in a local Swift package, connect the Kotlin framework generated from the multiplatform project to your Xcode project:

  1. In Xcode, go to Product | Scheme | Edit scheme or click the scheme icon in the top bar and select Edit scheme:

    Edit scheme

  2. Select the Build | Pre-actions item, then click + | New Run Script Action:

    New run script action

  3. Adjust the following script and add it as an action:

    cd "<Path to the root of the multiplatform project>"
./gradlew :<Shared module name>:embedAndSignAppleFrameworkForXcode

    • In the cd command, specify the path to the root of your Kotlin Multiplatform project, for example, $SRCROOT/...

    • In the ./gradlew command, specify the name of the shared module, for example, :shared or :composeApp.

  4. Choose your app's target in the Provide build settings from section:

    Filled run script action

  5. You can now import the shared module into your local Swift package and use Kotlin code.

    In Xcode, navigate to your local Swift package and define a function with a module import, for example:

    import Shared

public func greetingsFromSpmLocalPackage() -> String {
    return Greeting.greet()
}
    SPM usage

  6. In the ContentView.swift file of your iOS project, you can now use this function by importing the local package:

    import SwiftUI
import SpmLocalPackage

struct ContentView: View {
    var body: some View {
        Vstack {
            Image(systemName: "globe")
                .imageScale(.large)
                .foregroundStyle(.tint)
            Text(greetingsFromSpmLocalPackage())
        }
        .padding()
    }
}

#Preview {
    ContentView()
}

  7. Build the project in Xcode. If everything is set up correctly, the project build will be successful.

There are a couple more factors worth considering:

  • If you have a custom build configuration that is different from the default Debug or Release, on the Build Settings tab, add the KOTLIN_FRAMEWORK_BUILD_TYPE setting under User-Defined and set it to Debug or Release.

  • If you encounter an error with script sandboxing, open the iOS project settings by double-clicking the project name, then on the Build Settings tab, disable the User Script Sandboxing under Build Options.

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