Implement Objective-C into C++. How?

Can you re-phrase your question? I don't understand.

Generally, when linking different languages, you have to find some lowest-common denominator. Both Objective-C and C++ speak plain old C, so you can use that. You can also use Objective-C++ but that would only allow your Objective-C code to accept C++.

Objective-C++ is the way to go here. What specifically is not working or are you having trouble with? Can you provide code examples?

The starting point to using Objective-C++ is to use the `.mm` file extension instead of `.m`. as a hint to Xcode that it's an Objective-C++ file, if you haven't discovered that detail yet.

Are you seeling to move from Objective-C to Objective-C++, or from Objective-C to C++?

If the former...

Some discussions of mixing C to C++ code, and moving from C to C++ code:

https://isocpp.org/wiki/faq/mixing-c-and-cpp

https://stackoverflow.com/questions/297122/what-should-i-keep-in-mind-when-porting-from-c-to-c

http://www.cplusplus.com/forum/articles/21017/

The C to C++ move is a bigger mental and bigger coding shift than is the Objective-C to Objective-C++ part of this effort.

If you don”t need the full capabilities of C++ in existing C code, extern “C” and a few tweaks is often enough to get the code compiling and going. Most existing C code will work, with few or no changes. The dragged-to-C++ code definitely won’t use very much of what C++ code can, but it’ll work.

If the latter...

If you’ve going from Objective-C code to C++ code, you’ll be re-writing all of the Objective part of the Objective-C code, and some far smaller part of the C code. This is no sam;l effort, as Objective-C and C++ are quite different. Depending on the existing code, this can approach or can be a wholesale source code re-write.