Optimizing iOS App - Crash Report

Question

I´m would like to optimize my app - i just downloaded the crash log from the organizer. I got the following crash 3 times. Has everyone a idea, what´s wrong?

Here is the code of the lines:

-(void)checkAnswer:(int)theAnswerValue {
    [holeView removeFromSuperview];
    [circleView removeFromSuperview];
    [self.circularProgressView removeFromSuperview];

    if(rightAnswer == theAnswerValue) {
    NSLog(@"Correct Answer");
    } else {
       NSLog(@"Wrong Answer");      
    }
    [self updateScore];
}

- (IBAction)buttonThree:(id)sender {
    audioPlayer = nil;
    NSInteger theAnswerValue = 3;
    [self checkAnswer:(int)theAnswerValue];
}

Would be great, if someone can help me out?! The regular order should be, that as soon as a button(Three) is pressed, the game should check the answer.