Kotlin/Native FAQ

Define a top-level function fun main(args: Array<String>) or just fun main() if you are not interested in passed arguments, please ensure it's not in a package. Also, compiler switch -entry could be used to make any function taking Array<String> or no arguments and return Unit as an entry point.

Kotlin/Native uses an automated memory management scheme that is similar to what Java or Swift provide.

Learn about the Kotlin/Native memory manager

Use the -produce dynamic compiler option or binaries.sharedLib() in your Gradle build file:

kotlin {
    iosArm64("mylib") {
        binaries.sharedLib()
    }
}

It produces a platform-specific shared object (.so on Linux, .dylib on macOS, and .dll on Windows targets) and a C language header, allowing the use of all public APIs available in your Kotlin/Native program from C/C++ code.

Complete the Kotlin/Native as a dynamic library tutorial

Use the -produce static compiler option or binaries.staticLib() in your Gradle build file:

kotlin {
    iosArm64("mylib") {
        binaries.staticLib()
    }
}

It produces a platform-specific static object (.a library format) and a C language header, allowing you to use all the public APIs available in your Kotlin/Native program from C/C++ code.

As Kotlin/Native needs to download a platform specific toolchain, you need to specify -Dhttp.proxyHost=xxx -Dhttp.proxyPort=xxx as the compiler's or gradlew arguments, or set it via the JAVA_OPTS environment variable.

Use the -module-name compiler option or matching Gradle DSL statement.

kotlin {
    iosArm64("myapp") {
        binaries.framework {
            freeCompilerArgs += listOf("-module-name", "TheName")
        }
    }
}

kotlin {
    iosArm64("myapp") {
        binaries.framework {
            freeCompilerArgs += ["-module-name", "TheName"]
        }
    }
}

The default name is for an iOS framework is <project name>.framework. To set a custom name, use the baseName option. This will also set the module name.

kotlin {
    iosArm64("myapp") {
       binaries {
          framework {
              baseName = "TheName"
          }
       }
    }
}

Bitcode embedding was deprecated in Xcode 14 and removed in Xcode 15 for all Apple targets. The Kotlin/Native compiler does not support bitcode embedding since Kotlin 2.0.20.

If you're using earlier versions of Xcode but want to upgrade to Kotlin 2.0.20 or later versions, disable bitcode embedding in your Xcode projects.

note

This issue is relevant for the legacy memory manager only. Check out Kotlin/Native memory management to learn about the new memory manager, which has been enabled by default since Kotlin 1.7.20.

It likely happens, because you are trying to mutate a frozen object. An object can transfer to the frozen state either explicitly, as objects reachable from objects on which the kotlin.native.concurrent.freeze is called, or implicitly (i.e. reachable from enum or global singleton object - see the next question).

note

This issue is relevant for the legacy memory manager only. Check out Kotlin/Native memory management to learn about the new memory manager, which has been enabled by default since Kotlin 1.7.20.

Currently, singleton objects are immutable (i.e. frozen after creation), and it's generally considered good practise to have the global state immutable. If for some reason you need a mutable state inside such an object, use the @konan.ThreadLocal annotation on the object. Also, the kotlin.native.concurrent.AtomicReference class could be used to store different pointers to frozen objects in a frozen object and automatically update them.

First, please consider trying preview versions.

In case you need an even more recent development version, you can build Kotlin/Native from source code: clone Kotlin repository and follow these steps.