Simple math app: answer always equals 1 - ios

Question

I'm new to programming so this is probably a result of my illiteracy, but I would appreciate a solution anyways.
I'm trying to make an app that takes the user input from 12 different textfields and feeds out an answer into a label by mathematically altering the user input using Cramer's rule.
So far, I've been trying to multiply the user input from one textfield by the user input from another and feed it out into a label, but whenever I type in my numbers, the product is always 1, and it doesn't print to the label.
Here is my code:
//
// ViewController.h
// Cramer
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController
// Objects are given addresses:
#property (weak, nonatomic) IBOutlet UITextField *box_a;
#property (weak, nonatomic) IBOutlet UITextField *box_b;
#property (weak, nonatomic) IBOutlet UILabel *hiLabel;
#property (weak, nonatomic) IBOutlet UIButton *clickButton;
#end
AND
//
// ViewController.m
// Cramer
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
// Math takes place:
- (IBAction)clickButton:(id)sender {
NSInteger number1 = [self.box_a.text integerValue];
NSInteger number2 = [self.box_b.text integerValue];
NSInteger prod = number1 * number2;
self.hiLabel.text = [NSString stringWithFormat:#"%#", #(prod)];
}
#end
Thanks

Answer 1

Use %ld as the format specifier in the last statement:
self.hiLabel.text = [NSString stringWithFormat:#"%ld", prod];