Leak from NSURL and AVAudioPlayer using ARC

Question

I am runung Instruments on an iPhone 4S. I am using AVAudioPlayer inside this method:

-(void)playSound{
    NSURL *url = [self.word soundURL];
    NSError *error;
    audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
    if (!error) {
        [audioPlayer prepareToPlay];
        [audioPlayer play];
    }else{
       NSLog(@"Problem With audioPlayer on general card. error : %@ | url %@",[error description],[url absoluteString]);
}

I am getting leaks when playing the sound files:

Leaked objects:

1.

Object: NSURL

Responsible Library: Foundation

Responsable Frame: Foundation -[NSURL(NSURL) allocWithZone:]

2.

Object: _NSCFString

Responsible Library: Foundation

Responsable Frame: Foundation -[NSURL(NSURL) initFileURLWithPath:]

Instruments does not point directly to my code so I find it hard to locate the leak reason.

MY QUESTION

What could cause the leak? OR How can I locate leaks when I am not responsible to the code?

EDIT This is the schema from Instruments cycles view: enter image description here Thanks Shani

are you debugging with zombies enabled? that can cause objects to remain in memory... — nielsbot
There's a bug in your code: You don't initialize error to nil, but you later test for !error. (APIs that take an NSError ** return are not guaranteed to set error unless the call fails. You must check audioPlayer != nil before using error. You should also initialize error to nil. — nielsbot
I looked at it--seems to be a possible leak in Apple's code.. The AVAudioPlayer instance 1. retains the passed in data/url and 2. creates an instance of AVAudioPlayerCpp which 3) also retains the passed in data/url. When the AVAudioPlayer is released, it releases the data/url, but I never see a release from the associated AVAudioPlayerCpp — nielsbot
I posted the "proof". maybe someone wants to double check... — nielsbot

nielsbot nielsbot · Accepted Answer · 2012-09-30T07:58:39

Looks to be a leak in Apple's code... I tried using both

-[AVAudioPlayer initWithData:error:] and
-[AVAudioPlayer initWithContentsOfURL:error:]

In the first case, the allocated AVAudioPlayer instance retains the passed in NSData. In the second, the passed in NSURL is retained:

I've attached some screen shots of the Instruments window showing the retain/release history for a passed in NSData object.

enter image description here

You can see the AVAudioPlayer object then creates a C++ object AVAudioPlayerCpp, which retains the NSData again:

enter image description here

Later, when the AVAudioPlayer object is released, the NSData is released, but there's never a release call from the associated AVAudioPlayerCpp... (You can tell from the attached image)

Seems you'll have to use a different solution to play media if you want to avoid leaking NSData/NSURL's..

Here's my test code:

-(void)timerFired:(NSTimer*)timer
{
    NSString * path = [[ NSBundle mainBundle ] pathForResource:@"song" ofType:@"mp3" ] ;

    NSError * error = nil ;
    NSData * data = [ NSData dataWithContentsOfFile:path options:NSDataReadingMapped error:&error ] ;
    if ( !data )
    {
        if ( error ) { @throw error ; }
    }

    AVAudioPlayer * audioPlayer = data ? [[AVAudioPlayer alloc] initWithData:data error:&error ] : nil ;
    if ( !audioPlayer )
    {
        if ( error ) { @throw error ; }
    }

    if ( audioPlayer )
    {
        [audioPlayer play];
        [ NSThread sleepForTimeInterval:0.75 ] ;
        [ audioPlayer stop ] ;
    }
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // ...
    [ NSTimer scheduledTimerWithTimeInterval:3.0 target:self selector:@selector( timerFired: ) userInfo:nil repeats:YES ] ;
    // ...
    return YES;
}

Leak from NSURL and AVAudioPlayer using ARC

5 Answers