How to find the leaky faucet that loads into Malloc 32kb

Question

I have been messing around with Leaks trying to find which function is not being deallocated (I am still new to this) and could really use some experienced insight.

I have this bit of code that seems to be the culprit. Every time I press the button that calls this code, 32kb of memory is additionally allocated to memory and when the button is released that memory does not get deallocated.

What I found was that everytime that AVAudioPlayer is called to play an m4a file, the final function to parse the m4a file is MP4BoxParser::Initialize() and this in turn allocates 32kb of memory through Cached_DataSource::ReadBytes

My question is, how do I go about deallocating that after it is finished so that it doesn't keep allocating 32kb every time the button is pressed?

Any help you could provide is greatly appreciated!

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

//stop playing
theAudio.stop;


// cancel any pending handleSingleTap messages 
[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(handleSingleTap) object:nil];

UITouch* touch = [[event allTouches] anyObject]; 


NSString* filename = [g_AppsList objectAtIndex: [touch view].tag];

NSString *path = [[NSBundle mainBundle] pathForResource: filename ofType:@"m4a"];  
theAudio=[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL];  
theAudio.delegate = self; 
[theAudio prepareToPlay];
[theAudio setNumberOfLoops:-1];
[theAudio setVolume: g_Volume];
[theAudio play];
}

Answer 1

This line looks culprit to me:

theAudio=[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL];  

When does this resource get released?

Answer 2

The trick to memory management in Cocoa is to balance out any calls to alloc, retain or copy with a subsequent call to release.

In this case, you are sending alloc to initialize your theAudio variable, but you are never sending release.

Assuming that you will only have one sound playing at a time, the best way to do this is with a property on your controller (the one that has this -touchesBegan method). The property declaration would look like this:

@property (nonatomic, retain) AVAudioPlayer * theAudio;

You will then need to set theAudio to nil in your init method:

theAudio = nil; // note: simple assignment is preferable in init

And be sure to release the variable in your dealloc method:

[theAudio release];

Now, your touchesBegan could look like this:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    //stop playing
    theAudio.stop;
    ...
    AVAudioPlayer * newAudio = [[AVAudioPlayer alloc] initWithContentsOfUrl:...];
    self.theAudio = newAudio; // it is automatically retained here...

    theAudio.delegate = self; 
    [theAudio prepareToPlay];
    [theAudio setNumberOfLoops:-1];
    [theAudio setVolume: g_Volume];
    [theAudio play];

    [newAudio release];       // ...so you can safely release it here
}