There are a few other open source IDE's but I don't really recommend them - most of them crash on opening in new versions of Mac OS X. That being said xcode supports multiple types of langauges, and has extensions for many more - and C++ can be spliced in with objective C code - so if you prefer to code in C++ you can write a quick objective C wrapper and do all your own stuff in C++ - or indeed the langauge of your choice. Xcode is the apple supplied IDE, and without external libraries some objective C is always required to build applications.
