App crashes after running a method once

Question

Probably a dumb mistake, but I just need to know why my app shuts down after I press the button. It gives the desired answer for a second or two and then shuts down. Why? Then it takes me to this:

1{
2    @autoreleasepool {
3        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
4    }
5}

Line 3 is shaded in green and says "Thread 1: signal SIGBART" on the right side.

This is the code:

- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    //dismiss the keyboard
    [textField resignFirstResponder];
    return YES;

}

@synthesize go;
@synthesize start;
@synthesize calc;
@synthesize answer;
@synthesize input;
@synthesize count;

- (void)updateTipTotals
{

    int fuzzy = [input.text intValue];


    //handle divide by 0
    if (fuzzy %3 == 0 && fuzzy % 7 == 0) {
        answer.text = @"Fuzzy Ducky";
    }else {
        if (fuzzy% 7 == 0) {
            answer.text = @"Ducky";
        }
        else {
            if (fuzzy % 3 == 0) {
                answer.text = @"Fuzzy";
            }else {
                answer.text = input.text;
            }
        }
    }

}

-(IBAction)calcTouchDown:(id)sender{

    [self updateTipTotals];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    //this informs the text fields the controller is their delegate
    input.delegate = self;
    start.delegate = self;

Answer 1

Try setting an exception breakpoint in Xcode before running. It should then highlight the line of code actually causing the crash.