How to use custom Objective-C object in C++? - c++

Question

I'm implementing some fast sort algorithms, and to get best performances, I'd like to use a C++ binding in Objective-C. But I want my algorithms to work with user custom objects and with something similar to a NSComparator ; which type may I use in C++ to use these objects ? May I template a class ?
Please let me know about your best solution to bind custom objects in C++ and to use a NSComparator in C++ ?
Best regards,
Hervé HL.

Answer 1

With the help of #Dave, I finally found the solution to extract pointers from NSArray, no matter the contained type, do some complex operations, and then reassemble the pointers, using void * type.
Just rename your .m file to .mm to enable Objective-C++ features.
void *array[[self count]]; //create an empty void* array
for (uint i = 0; i < [self count]; i++)
{
int address = (int)[self objectAtIndex:i];
array[i] = (void *)address; //insert NSObjects pointers into void* array
}
To get back the NSObjects from void* array, just proceed like this:
NSMutableArray *doneAr = [[NSMutableArray alloc] init]; //create a NSMutableArray
for (uint i = 0; i < [self count]; i++)
{
void *tmp = (void **)done + i; //extract the pointer in the void* array
NSString *strTmp = (NSString *)(*((Class *)tmp)); //convert it back to origin type (here NSString *)
[doneAr addObject:strTmp]; //add it back to the previously created NSMutableArray
}
Hope this answer could be helpful for future issues. If you wish to use NSComparator like me in your C++ implementation, just rename your .m file into .mm file so as you can use Objective-C++ features ; then import and use what you need (NSComparator for example).