Interacting with C++ classes from Swift -

i have significant library of classes written in c++. i'm trying make use of them through type of bridge within swift rather rewrite them swift code. primary motivation c++ code represents core library used on multiple platforms. effectively, i'm creating swift based ui allow core functionality work under os x.

there other questions asking, "how call c++ function swift." not question. bridge c++ function, following works fine:

define bridging header through "c"

#ifndef imagereader_hpp #define imagereader_hpp  #ifdef __cplusplus extern "c" { #endif      const char *hexdump(char *filename);     const char *imagetype(char *filename);  #ifdef __cplusplus } #endif  #endif /* imagereader_hpp */ 

swift code can call functions directly

let type = string.fromcstring(imagetype(filename)) let dump = string.fromcstring(hexdump(filename)) 

my question more specific. how can instantiate , manipulate c++ class within swift? can't seem find published on this.

i've worked out manageable answer. how clean you'd entirely based upon how work you're willing do.

first, take c++ class , create c "wrapper" functions interface it. example, if have c++ class:

class mbr {     std::string filename;  public:     mbr (std::string filename);     const char *hexdump();     const char *imagetype();     const char *bootcode();     const char *partitions(); private:     bool readfile(unsigned char *buffer, const unsigned int length); }; 

we implement these c++ functions:

#include "mbr.hpp"  using namespace std; const void * initialize(char *filename) {     mbr *mbr = new mbr(filename);      return (void *)mbr; }  const char *hexdump(const void *object) {     mbr *mbr;     static char retval[2048];      mbr = (mbr *)object;     strcpy(retval, mbr -> hexdump());     return retval; }  const char *imagetype(const void *object) {     mbr *mbr;     static char retval[256];      mbr = (mbr *)object;     strcpy(retval, mbr -> imagetype());     return retval; } 

the bridge header contains:

#ifndef imagereader_hpp #define imagereader_hpp  #ifdef __cplusplus extern "c" { #endif      const void *initialize(char *filename);     const char *hexdump(const void *object);     const char *imagetype(const void *object);  #ifdef __cplusplus } #endif  #endif /* imagereader_hpp */ 

from swift, can instantiate object , interact so:

let cppobject = unsafemutablepointer<void>(initialize(filename)) let type = string.fromcstring(imagetype(cppobject)) let dump = string.fromcstring(hexdump(cppobject))                 self.imagetypelabel.stringvalue = type! self.dumpdisplay.stringvalue = dump! 

so, can see, solution (which rather simple) create wrappers instantiate object , return pointer object. can passed wrapper functions can treat object conforming class , call member functions.

making cleaner

while fantastic start , proves feasible use existing c++ classes trivial bridge, can cleaner.

cleaning mean remove unsafemutablepointer<void> middle of our swift code , encapsulate swift class. essentially, use same c/c++ wrapper functions interface them swift class. swift class maintains object reference , passes method , attribute reference calls through bridge c++ object!

having done this, of bridging code encapsulated in swift class. though still using c bridge, using c++ objects transparently without having resort recoding them in objective-c or objective-c++.