How can I build C++ code into .framework with cinterop?

Multiplatform
1

I’m doing a Multiplatform project, and want build a .framework for iOS platform.
I have to use C++ code in the project.

My project structure:

src/commain/cpp/cinterop.def
src/iosMain/cpp/NativeIF.cpp
src/iosMain/cpp/NativeIF.h
src/iosMain/cpp/CppImplement.cpp
src/iosMain/cpp/CppImplement.h
…other cpp source code

The code in src/commain/cpp/cinterop.def:

headers = NativeIF.h
package = my.package.name

The code in src/iosMain/cpp/NativeIF.h

#ifdef __cplusplus
extern "C" {
#endif
void NativeInterface_1();
void NativeInterface_2();
#ifdef __cplusplus
}
#endif

The code in src/iosMain/cpp/NativeIF.cpp

#include "NativeIF.h"

#ifdef __cplusplus
extern "C" {
#endif

    void NativeInterface_1() {
        // some code of calling CppImplement.cpp
    }

    void NativeInterface_2() {
        // some code of calling CppImplement.cpp
    }

#ifdef __cplusplus
}
#endif

In my build.gradle.kts, I config the ios platform

val xcf = XCFramework(sdkName)
  listOf(
    iosX64(),
    iosArm64(),
    iosSimulatorArm64(),
  ).forEach {
    it.binaries.framework {
      baseName = "mylibname"
      binaryOption("bundleId", "$bundleIdCommon.ios")
      binaryOption("bundleShortVersionString", sdkVersion)
      xcf.add(this)
      isStatic = true
    }

    it.compilations.getByName("main") {
      cinterops {
        val infomatchingNativeLib by cinterops.creating {
          defFile(project.file("src/commonMain/cpp/cinterop.def"))
          compilerOpts("-I/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/usr/include/c++/v1")
          compilerOpts("-Isrc/iosMain/cpp")
          compilerOpts("-Isrc/commonMain/cpp/")
          ...other cpp files path
        }
      }
    }
  }

The current situation is, the .framework file can be build successfully, and I can find the klib file in path of build/classes/kotlin/iosXXX/main/cinterop.
But when I import this .framework into my xcode project, and build, there will be errors:

ld: Undefined symbols:
  _NativeInterface_1, referenced from:
      _my_package_name_NativeInterface_1_wrapper0 in mylibname[arm64][2](mylibname.framework.o)
  _NativeInterface_2, referenced from:
      _my_package_name_NativeInterface_2_wrapper0 in mylibname[arm64][2](mylibname.framework.o)
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I tried to write the implement of interface in cinterop.def directly, and wrap C++ implement with C.
But this way leads another link error in Xcode building: the C wrapper function of C++ can not be found.

What should I do to resove this problem?
Andbody can give me some advices?
Thanks very much.

PS:

  1. I use the .framework in a Swift project.
  2. I tried to use nm command to find the “NativeInterface_1” and “NativeInterface_2” in the .framework file, the result is:
U _NativeInterface_1
U _NativeInterface_2