SoundForest for iPhone
In this day and age, you don’t have to be a dedicated musician to try composing songs. Take SoundForest for iPhone: it is an elegant app with a bunch of musical elements that you can tap on to create custom tunes. SoundForest has 160 elements, 4 musical environments and 6 pitch levels for each music note.
You can tap on instruments and mix them to produce music on your iPhone and iPad. The app is available as a free download but you can unlock everything for under $2.