malloc错误和模拟器崩溃

这个 echoTime 一个按钮正在调用函数。当我在计时器结束前再次按下按钮时,它会给我一个malloc错误。当我在计时器结束后按下按钮再次启动时,模拟器挂起。

有人知道下面这段代码有什么问题吗

-(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];
    }
}