Sound overlapping with multiple button presses

Declare your AVAudioPlayer in the header the viewController ( don’t alloc a new one each time you play a sound). That way you will have a pointer you can use in a StopAudio method.

@interface myViewController : UIViewController <AVAudioPlayerDelegate> { 
    AVAudioPlayer *theAudio;
}
@property (nonatomic, retain) AVAudioPlayer *theAudio;
@end


@implementation myViewController
@synthesize theAudio;
- (void)dealloc {
    [theAudio release];
}
@end



- (void)playOnce:(NSString *)aSound {
    NSString *path = [[NSBundle mainBundle] pathForResource:aSound ofType:@"caf"];
    if(!theAudio){
        theAudio = [[AVAudioPlayer alloc] initWithContentsOfURL: [NSURL fileURLWithPath:path] error:NULL];
    }
    [theAudio setDelegate: self];
    [theAudio setNumberOfLoops:0];
    [theAudio setVolume:1.0];
    [theAudio play];
}

- (void)playLooped:(NSString *)aSound {
    NSString *path = [[NSBundle mainBundle] pathForResource:aSound ofType:@"caf"];
    if(!theAudio){
        theAudio = [[AVAudioPlayer alloc] initWithContentsOfURL: [NSURL fileURLWithPath:path] error:NULL];
    }
    [theAudio setDelegate: self];
    // loop indefinitely
    [theAudio setNumberOfLoops:-1];
    [theAudio setVolume:1.0];
    [theAudio play];
}

- (void)stopAudio {
    [theAudio stop];
    [theAudio setCurrentTime:0];
}

also be sure to read the Apple Docs