AVAudioPlayer crash after playing from an AVAudioRecorder

Question

I've got a button the user tap to start recording and tap again to stop. When it stop I want the recorded voice 'echo' back so the user can hear what was recorded. This works fine the first time. If I hit the button for the third time, it starts a new recording and when I hit stop it crashes with EXC_BAD_ACCESS.

- (IBAction) readToMeTapped {

        if(recording)

        {
        recording = NO;
        [readToMeButton setTitle:@"Stop Recording" forState: UIControlStateNormal ];    

        NSMutableDictionary *recordSetting = [[NSDictionary alloc] initWithObjectsAndKeys:
         [NSNumber numberWithFloat: 44100.0],                 AVSampleRateKey,
         [NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey,
         [NSNumber numberWithInt: 1],                         AVNumberOfChannelsKey,
         [NSNumber numberWithInt: AVAudioQualityMax],         AVEncoderAudioQualityKey,
         nil];

        // Create a new dated file
        NSDate *now = [NSDate dateWithTimeIntervalSinceNow:0];
        NSString *caldate = [now description];          
        recordedTmpFile = [NSURL fileURLWithPath:[[NSString stringWithFormat:@"%@/%@.caf", DOCUMENTS_FOLDER, caldate] retain]];
        error = nil;
        recorder = [[ AVAudioRecorder alloc] initWithURL:recordedTmpFile settings:recordSetting error:&error];
        [recordSetting release];
        if(!recorder){
            NSLog(@"recorder: %@ %d %@", [error domain], [error code], [[error userInfo] description]);
            UIAlertView *alert =
            [[UIAlertView alloc] initWithTitle: @"Warning"
                                       message: [error localizedDescription]
                                      delegate: nil
                             cancelButtonTitle:@"OK"
                             otherButtonTitles:nil];
            [alert show];
            [alert release];
            return;
        }


        NSLog(@"Using File called: %@",recordedTmpFile);
        //Setup the recorder to use this file and record to it.

        [recorder setDelegate:self];
        [recorder prepareToRecord];

        [recorder recordForDuration:(NSTimeInterval) 5]; //recording for a limited time

    }
    else
    { // it crashes the second time it gets here!
        recording = YES;            
        NSLog(@"Recording YES Using File called: %@",recordedTmpFile);
        [readToMeButton setTitle:@"Start Recording" forState:UIControlStateNormal ];

        [recorder stop]; //Stop the recorder.

        //playback recording
        AVAudioPlayer * newPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:recordedTmpFile error:&error];
        [recordedTmpFile release];

        self.aPlayer = newPlayer;
        [newPlayer release];

        [aPlayer setDelegate:self];
        [aPlayer prepareToPlay];
        [aPlayer play];
        }   
}

- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)sender successfully:(BOOL)flag {

        NSLog (@"audioRecorderDidFinishRecording:successfully:");

        [recorder release];
        recorder = nil;
}

Checking the debugger, it flags the error here

@synthesize aPlayer, recorder;

This is the part I don't understand. I thought it may have something to do with releasing memory but I've been careful. Have I missed something?

Answer 1

Did you make sure that @property (retain) does not include nonatomic? I'm thinking that some of the code that accesses those properties may be doing so from another thread. Also, you should always access those properties via their getters by using self.recorder and self.player, in order to make sure they are accessed within their respective locks.

Answer 2

After working on it for a while I stumbled on this debugging tip. It showed me that AVAudioPlayer was deallocated the second time around, causing the crash. So the Delegate must have done the clean up? I checked this SO thread and it is suggestion that the Delegate does not deallocate. However, if I remove the line

   [newPlayer release]; 

My program works! After reading this SO thread, I believe my issue is that I should implement AVAudioPlayerDelegate's - (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag method and release the audio player there, after the sound is done playing. I had done it for AVAudioRecorder.