Armony Circular Sequencer App
This sequencer also features scaling- don’t know if there is a circle of fifth-type of selecting your own scales since a 3rd window allows you to select it by name.
sent request about MIDI.. not yet, Filippo says. But coming..
The first circle, (shown here) is the sequencer (two tracks, 16 steps). The second circle (see appstore) allows to choose a degree of a scale. This stepsequencer therefore always produces music flawlessly (tonal errors ..)
In settings you can choose the scale and tone.
Armony for iPhone 3GS, iPhone 4, iPhone 4S, iPhone 5, iPod touch (3rd generation), iPod touch (4th generation), iPod touch (5th generation) and iPad on the iTunes App Store.