Star Composer was released a couple of years ago on the app store and had over 1.5 million copies downloaded. It's still one of the fastest selling apps of all time!

 

I composed, recorded and produced the loops for each style of music (oh... and the XMAS & Chinese new year version!!) with Olivier Behzadi. Have a look at P4S' site, you can link up to the app store from there - the app is free and you get a couple of musical genres to play with.

 

Even if you're the most musically untalented goon you can still make songs with this, it's pretty genius...