In objective C, you will love the Foundation framework. The matter with objective C is that you won't need to get stuck into stupid programmatic problems, and you will only get involved with the solution of your problem. C++ can suffer from some very annoying simple problems, sometimes, which cannot be work-arounded easily.
But there are 2 things in C++ that really make things easier for me: The memory management handling (and the way deconstructors are made in classes), and the operator overloading (the entire STL is based upon it) which is the foundation for very elegant classes. C++ has more low-level flexibility than Objective C, but Objective C is quicker to design, and more productive.
That said, I think Objective-C's way of handling memory is brilliant, but difficult for beginners.
Finally, I should say that a professional program can be built with ObjC or C++, and still have the same functionality, and the same features, and the same performance, so the choice of language will only be based upon the preference of the programmer alone. However, you should note that ObjC support in windows frameworks and in Windows in general, is nearly non-existent.