STTwitter is great, use it.
Few years ago I was making my first Twitter related app with MGTWitterEngine. While things kind of work, it wasn't a nice experience. It has been discontinued anyway.
Twitter then changed it's API, upgraded to 1.1, so MGTwitterEngine doesn't work. Some people created their own fork to implement stream API and more, but most of them are not continued because Twitter hates 3rd party developers.
Luckily we have STTwitter now, a stable, new library which integrate with ACAccount, the API for people to access OS's social network account. I've tried some simple task, such as connection stream api and sending tweets, everything works like a charm.