You can use BeatMaker 2 to send MIDI to other music apps running in the background.
This is a great way to sequence and control other synthesizers, samplers with BeatMaker 2.
Most recent music apps support background audio and MIDI input.
In this small guide, we'll control Sunrizer (http://itunes.apple.com/pl/app/sunrizer ... 63267?mt=8):
- In Sunrizer, activate background audio (upper left button) 'AUDIO BKG'
- In BeatMaker 2, press the "i" button on the studio, then MIDI SETUP, and toggle MIDI "OUT"
- In BeatMaker 2, create an empty keyboard instrument, and start playing
iOS Musician has a video showcasing the background MIDI features of music apps.
It's available here: http://youtu.be/2Y2Br7WhVDw
(Minimum requirements: iOS 4.3)