Unfortunately, the world of technology for music is not as forward as many other areas. It is understandable. To teach a musician, you have to told how to old your body, arms, hands, and fingers correctly. There are a few apps that can be bought to "teach" music, but in all honesty, it isn't something that I would use in everyday life.
It is cool to see everything out there and there are a few good apps that I have downloaded like metronomes and tuners, but as for now - that is all.