Hey there! :wave: I'm trying to pack the classes ...

# ios

[Bastian]

Hey there! 👋

I'm trying to pack the classes of a cinterop multiplatform dependency into the shared.framework for my iOS app (to make them available). The dependency uses cinterop as it's wrapping a C library. I'm already trying to export it via the Gradle setup (see setup in the thread). Though when building in either Xcode or AppCode, I get an error about missing symbols for architecture x86_64 and a warning that the dependency can't be exported (see error log in the thread).

I tried fixing this by including the .def file of the wrapping dependency and the include folder of the C library itself and making the export transitive. But this didn't help.

I'm using Kotlin 1.5.31.

[Bastian]

setup

omitted android setup and rest of file for brevity

kotlin {
    ios {
        binaries {
            framework {
                baseName = "shared"
                export("io.github.matrixkt:client:$matrixKtVersion")
                export("io.github.matrixkt:olm:$matrixKtVersion")
            }
        }
        compilations.getByName("main") {
            val libolm by cinterops.creating {
                defFile(project.file("libolm.def"))
                includeDirs(projectDir.resolve("include"))
            }
        }
    }

    sourceSets {
        val commonMain by getting {
            dependencies {
                implementation("org.jetbrains.kotlin:kotlin-stdlib-common")
                implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutineVersion")
                implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.2.2")
                implementation("io.ktor:ktor-client-core:$ktorVersion")
                api("io.github.matrixkt:client:$matrixKtVersion")
                api("io.github.matrixkt:olm:$matrixKtVersion") {
                    // android target will pick up "aar" version instead (see androidMain)
                    exclude(group="net.java.dev.jna", module="jna")
                }
                implementation("org.matrix.gitlab.matrix-org:olm:3.2.4")
            }
        }

        val iosMain by getting {
            dependencies {
                implementation("io.ktor:ktor-client-ios:$ktorVersion")

                implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutineVersion") {
                    version {
                        strictly(coroutineVersion) // still got to enforce
                    }
                }
            }
        }
    }
}

[Bastian]

error when building
both in AppCode and Xcode

_omitted some "_olm" missing references for brevity_

> Task :shared:cinteropLibolmIosX64 UP-TO-DATE
> Task :shared:compileKotlinIosX64 UP-TO-DATE
> Task :shared:linkDebugFrameworkIosX64
w: Interop library /Users/bc/.gradle/caches/modules-2/files-2.1/io.github.matrixkt/olm-iosx64/0.1.5/7175481a6a0031fc9611b550bbcf7658d69c6d4f/olm-cinterop-libolm can't be exported with -Xexport-library
e: /Applications/Xcode-12.5.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld invocation reported errors

The /Applications/Xcode-12.5.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld command returned non-zero exit code: 1.
output:
Undefined symbols for architecture x86_64:
  "_olm_sas_set_their_key", referenced from:
      _colm_internal_olm_sas_set_their_key_wrapper130 in result.o

...

  "_olm_outbound_group_session_message_index", referenced from:
      _colm_internal_olm_outbound_group_session_message_index_wrapper30 in result.o
ld: symbol(s) not found for architecture x86_64

> Task :shared:linkDebugFrameworkIosX64 FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':shared:linkDebugFrameworkIosX64'.
> Compilation finished with errors

[Bastian]

So I was able to solve it.

All I had to do was
• ✅ make sure the Kotlin Multiplatform dependency had C-Bindings for iOS Architectures
• ✅ compile the C-dependency of my dependency for iOS myself (as there were no prebuilts) (Found an iOS wrapper project, which luckily had a Package.swift defining a target for only the C-dependency) So I could use xcodebuild to compile the lib
• ✅ put the built library into my KM project
• ✅ link it in my binaries { framework { ... }}