Calling an objective c method using a function pointer from a c++ method -

i have c++ class needs call objective c method using pointer method. method returns void , takes argument of type 'status' status simple integral enum.

 enum status  {        status_valid = 0,        status_invalid,        status_unknown  }; 

i have pointer obj-c method set this. pointer method being passed c++ class and

typedef void (*funcptr) (status); funcptr myobjcselectorpointer = (void (*)(status))[self methodforselector:@selector(statuschanged: )]; cppclassinstance->setfuncpointer(myobjcselectorpointer) 

myobjcselectorpointer being held on cppclass this:

void cppclass::setfuncpointer(functptr *ptr) {      this->funcptr = ptr; } 

now somewhere else, when try call method pointed pointer, this:

status s; funcptr(s); 

the method gets called correctly, value passed method lost. obj-c method receives random value. when try call method in cpp class using same way, passes , receives correct value.

what doing wrong? can not call objective c method this?

the problem function signature of objective-c methods not simple might think.

in order make object-oriented programming possible, objective-c methods take 2 implicit arguments: id self, sel _cmd, calling object , selector sent - these need passed. need object call method on, , should store selector too. then, change function type definition correct one:

typedef void (*funcptr) (id, sel, status); 

to read: [1], [2] (near part typedef id (*imp)(id, sel, ...))