How to pass and return an object to a C++ function called from iOS Swift?

Question

In my iOS project, I want to call a C++ function from my Swift code that takes an object from my Swift code and returns another object.

So far, following this tutorial and adding a little bit more stuff, I managed to call a C++ function that takes a simple parameter and returns a string:

• I create the NativeLibWrapper.h file:

#import <Foundation/Foundation.h>

@interface NativeLibWrapper : NSObject

- (NSString *) sayHello: (bool) boolTest;

@end

• I create the NativeLibWrapper.mm file:

#import <Foundation/Foundation.h>

#import "NativeLibWrapper.h"
#import "NativeLib.hpp"

@implementation NativeLibWrapper

- (NSString *) sayHello: (bool) boolTest {
    NativeLib nativeLib;
    std::string retour = nativeLib.sayHello(boolTest);
    return [NSString stringWithCString: retour.c_str() encoding: NSUTF8StringEncoding];
}

@end

• I create the NativeLib.hpp file:

#ifndef NativeLib_hpp
#define NativeLib_hpp

#include <stdio.h>
#include <string>

class NativeLib
{
public:
    std::string sayHello(bool boolTest);
};

#endif /* NativeLib_hpp */

• I create the NativeLib.cpp file:

#include "NativeLib.hpp"

std::string NativeLib::sayHello(bool boolTest)
{
    return "Hello C++ : " + std::to_string(boolTest);
}

• I add the following in Runner/Runner/Runner-Bridging-Header.h:

#import "NativeLibWrapper.h"

• And finally, I call the C++ function in Swift:

NativeLibWrapper().sayHello(true)

But now, let's say that my C++ sayHello() function takes this kind of object as a parameter (so I can access it in the C++ function):

class TestAPOJO {

    var value1 = ""
    var value2 = false
}

and returns this kind of object (generated from the C++ function but then mapped into a Swift object, or something like that):

class TestBPOJO {

    var value3 = 0.0
    var value4 = false
}

How can I achieve that?

Thanks.