The International Phonetic Alphabet (IPA) is not a language but a set of agreed special symbols for describing the pronunciation of any language. Within Unicode they are spread over a number of different blocks, and your OS X should be able to display them with the right fonts. The Wikipedia IPA page is a good way to test your fonts, as the charts there are available both as text and as images.
To input IPA in OS X you need to use the app IPA Palette, the OS X Character Palette, or a special keyboard, such as that created by SIL. Any modern word processor should work.