There's a tutorial on how to capture midi events from a MusicSequence
here (such as note on/off): http://www.deluge.co/?q=midi-driven-animation-core-audio-objective-c
In brief, the method is to call MIDIDestinationCreate
to create your own MIDI endpoint to handle the MIDI messages, and then point your MusicSequence
at it with MusicSequenceSetMIDIEndpoint
.