Will it do C++? I still haven't found a good C++ editor (with class member autocomplete popups and such) - at least, nothing that compares to Visual Studio over in the Windows world.
screenshot appears to be C++ code (might be wrong on this though, as I've never written any C++, and only use C occasionally)
The screenshot displays C code.
gcc and vim with proper c++ handling work really well for me.
Why not Xcode?
The popup with the list of class members (I think XCode calls it "Code Sense") tends not to work if your code is too complicated. I know that sounds like a silly reason not to use an IDE, but I surprise myself with how much I miss it.