When is a MIDINoteMessage played in a MusicTrack? iOS - ios

Question

I'm creating a MusicTrack of MIDI Notes that are successfully played using
MusicPlayerStart(sequencePlayer)
But I would like to know when are they played, so I can update the UI for each MIDI Note played.
// Creating MIDI Track
MusicTrack track;
UInt32 trackIndex = 0;
musicTrackAtIndex(trackIndex, &track);
//Adding Tempo
addTempoEvent(0.0, 120);
// Adding MIDI notes
const int channel = 0;
MIDINoteMessage note;
note.channel = channel;
note.velocity = 100.0;
note.duration = 0.3;
note.releaseVelocity = 0;
note.note = 68;
addMIDINoteToTrack(track, note, 1);
note.note = 78;
addMIDINoteToTrack(track, note, 2);
note.note = 88;
addMIDINoteToTrack(track, note, 3);
note.note = 98;
addMIDINoteToTrack(track, note, 4);
MusicTimeStamp trackEnd = 4;
addEndOfTrackAtTime(trackEnd);
setLoopTrack(true);
playSequence();
EDIT
Showing in more detail how I'm building the MIDI Track.
-(void) playing4NotesInLoop {
MusicTrack musicTrack;
MusicSequence musicSequence;
MusicPlayer musicPlayer;
const int loop_length = 4;
NewMusicSequence(&musicSequence);
// Create a client
MIDIClientRef virtualMidi;
MIDIClientCreate(CFSTR("Virtual Client"),
MyMIDINotifyProc,
NULL,
&virtualMidi);
// Create an endpoint
MIDIEndpointRef virtualEndpoint;
MIDIDestinationCreate(virtualMidi, #"Virtual Destination", MyMIDIReadProc, self.samplerUnit, &virtualEndpoint);
MusicSequenceNewTrack(musicSequence, &musicTrack);
MIDINoteMessage aMessage;
aMessage.channel = 1;
aMessage.duration = 0.5f;
aMessage.velocity = 100;
for(int i=0; i<4; ++i)
{
if (i==0) {
aMessage.note = 30;
}else {
aMessage.note = 60;
}
MusicTrackNewMIDINoteEvent(musicTrack, i, &aMessage);
}
MusicTrackLoopInfo loop_info;
loop_info.loopDuration = loop_length;
loop_info.numberOfLoops = 0;
MusicTrackSetProperty(musicTrack, kSequenceTrackProperty_LoopInfo, &loop_info, sizeof(MusicTrackLoopInfo));
MusicTimeStamp track_length;
track_length = loop_length;
MusicTrackSetProperty(musicTrack, kSequenceTrackProperty_TrackLength, &track_length, sizeof(MusicTimeStamp));
MusicSequenceSetMIDIEndpoint(musicSequence, virtualEndpoint);
NewMusicPlayer(&musicPlayer);
MusicPlayerSetSequence(musicPlayer, musicSequence);
MusicPlayerStart(musicPlayer);
}
With this code I'm successfully playing a loop of 4 notes, a MusicSequenceSetMIDIEndpoint(musicSequence, virtualEndpoint) has been set up specifying the read proc. I used the same code but loading a MIDI file and the read proc it's successfully called for each note.

Answer 1

You create a virtual endpoint with MIDIDestinationCreate and then call MusicSequenceSetMIDIEndpoint to connect your sequence to it. The read proc that you specify will be called on each event.