MusicTrack Problem

ViewController.m

#import "ViewController.h"
#import <AudioToolbox/AudioToolbox.h>
#import <AudioUnit/AudioUnit.h>

const int loop_length = 4;

@interface ViewController()

-(OSStatus) InitMIDI;

@property (assign) MusicTrack musicTrack;

@end



@implementation ViewController


@synthesize musicTrack = _musicTrack;


- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
	
	//[self BuildAUGraph];
	[self InitMIDI];
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
}

- (void)viewWillDisappear:(BOOL)animated
{
	[super viewWillDisappear:animated];
}

- (void)viewDidDisappear:(BOOL)animated
{
	[super viewDidDisappear:animated];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
	if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
	    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
	} else {
	    return YES;
	}
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
	MusicTrackClear(_musicTrack, 0, loop_length);
	
	MIDINoteMessage aMessage;
	aMessage.channel = 1;
	aMessage.velocity = 98;
	aMessage.duration = 0.5f;
	aMessage.note = 60;
	
	for(int i=0; i<loop_length; ++i)
	{
		MusicTrackNewMIDINoteEvent(_musicTrack, i, &aMessage);
	}
}


//**************************************************************************************************
-(OSStatus) InitMIDI
{
	OSStatus result = noErr;
	
	//create sequence
	MusicSequence sequence;
	result = NewMusicSequence(&sequence);
	
	
	//create track
	result = MusicSequenceNewTrack(sequence, &_musicTrack);
	
	MIDINoteMessage aMessage;
	aMessage.channel = 1;
	aMessage.velocity = 98;
	aMessage.duration = 0.5f;
	aMessage.note = 60;
	
	for(int i=0; i<loop_length; ++i)
	{
		MusicTrackNewMIDINoteEvent(_musicTrack, i, &aMessage);
	}
	
	MusicTrackLoopInfo loop_info;
	loop_info.loopDuration = loop_length;
	loop_info.numberOfLoops = 0;
	
	result = MusicTrackSetProperty(_musicTrack, kSequenceTrackProperty_LoopInfo, &loop_info, sizeof(MusicTrackLoopInfo));
	
	MusicTimeStamp track_length;
	track_length = loop_length;
	
	result = MusicTrackSetProperty(_musicTrack, kSequenceTrackProperty_TrackLength, &track_length, sizeof(MusicTimeStamp));
	
	//create player
	MusicPlayer player;
	result = NewMusicPlayer(&player);
	result = MusicPlayerSetSequence(player, sequence);
	
	result = MusicPlayerStart(player);

	return result;
}

@end