malloc error and simulator crash - objective-c

Question

I constantly get malloc error : double freed....
The echoTime function is being called by a button. When I press the button again before the timer ends it gives me the malloc error. When I press the button after the timer finished to start it again, the simulator hangs.
Does anyone know what is wrong with the following piece of code:
-(IBAction)echoTime: (id) sender {
if (gameTimer != nil) {
[gameTimer invalidate];
[gameTimer release];
}
NSInteger secs = 1 * 60;
if (secs != 0) {
NSNumber *elapsedSeconds = [[NSNumber alloc] initWithInt:secs];
NSDictionary *myDict = [NSDictionary dictionaryWithObject:elapsedSeconds forKey:#"TotalSeconds"];
gameTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(echoIt:) userInfo:myDict repeats: YES];
}
}
-(void)echoIt: (NSTimer *) timer {
NSNumber *num = (NSNumber *) [[timer userInfo] valueForKey:#"TotalSeconds"];
seconds++;
NSInteger sec = [num integerValue] - seconds;
NSInteger minutes = sec / 60;
[gameTimeLabel setText:[NSString stringWithFormat:#"%02i:%02i", minutes, sec-(60*minutes)]];
if (sec == 0) {
[self playSound:#"Horn"];
[gameTimer invalidate];
}
}

Answer 1

NSNumber *elapsedSeconds = [[NSNumber alloc] initWithInt:secs];
In general dont alloc NSNumbers and a NSDictionary (and NSArray,NSSet) always retains the objects it is given (and releases them too when it should).
try...
NSNumber *elapsedSeconds = [NSNumber numberWithInt:secs];
It'll stop the retain cycle you've got and might stop the crash.
Also irrelevant but stylewise.
NSInteger secs = [[[timer userInfo] valueForKey:#"TotalSeconds"] intValue];
Is a little more efficient.