Can I connect my acoustic guitar to my iPad and Garageband?

I'm a newbie, so please forgive me. I have a very nice USB mic and can record my acoustic guitar to my ipad/garageband that way. But I want to know, could I purchase acoustic pickups and record in garageband, taking advantage of some of the effects offered? I know I'd need iRig or something, but will it work?

Thanks everyone!

You can get acoustic pickups, or you can get a decent mic that will also work with iRig. A friend of mine just uses a mic for his acoustic guitars. it works well.