Listing 28.16 produces run time error

Swift Programming: The Big Nerd Ranch Guide (2nd E 28. Interoperability
1

Hi, I am having a problem getting the Contacts app to run when I click on the add + button. I get the following error messages;

2017-10-27 15:42:33.335036+0100 Contacts[41021:3407855] [MC] Lazy loading NSBundle MobileCoreServices.framework
2017-10-27 15:42:33.335664+0100 Contacts[41021:3407855] [MC] Loaded MobileCoreServices.framework
2017-10-27 15:42:33.350694+0100 Contacts[41021:3407855] [MC] System group container for systemgroup.com.apple.configurationprofiles path is /Users/StephenLearmonth/Library/Developer/CoreSimulator/Devices/A0EB4B24-60D5-4029-B217-A0B0A61C4163/data/Containers/Shared/SystemGroup/systemgroup.com.apple.configurationprofiles
fatal error: unexpectedly found nil while unwrapping an Optional value
2017-10-27 15:42:33.354515+0100 Contacts[41021:3407855] fatal error: unexpectedly found nil while unwrapping an Optional value
(lldb)

Here is my Swift code in NewContactViewController.swift;

//  NewContactViewController.swift
//  Contacts
//
//  Created by Stephen Learmonth on 25/10/2017.
//  Copyright © 2017 BigNerdRanch. All rights reserved.
//

import UIKit

class NewContactViewController: UIViewController {
    @IBOutlet var firstNameTextField: UITextField!
    @IBOutlet var lastNameTextField: UITextField!
    @IBOutlet var contactImageView: UIImageView!
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Do any additional setup after loading the view
        contactImageView.image = ImageFactory.generateDefaultImage(of: contactImageView.frame.size)

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    

    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}

and here is my Objective-C code for ImageFactory.m

//  ImageFactory.m
//  Contacts
//
//  Created by Stephen Learmonth on 27/10/2017.
//  Copyright © 2017 BigNerdRanch. All rights reserved.
//

#import "ImageFactory.h"

@implementation ImageFactory

+ (UIImage *)generateDefaultImageOfSize:(CGSize)size
{
    //Make Frame and get context
    CGRect frame = CGRectMake(0, 0, size.width, size.height);
    UIGraphicsBeginImageContext(size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    // Draw white background and yellow circle
    CGContextSetFillColorWithColor(context, [[UIColor whiteColor] CGColor]);
    CGContextFillRect(context, frame);
    CGContextSetFillColorWithColor(context, [[UIColor yellowColor] CGColor]);
    CGContextFillEllipseInRect(context, frame);
    
    CGFloat x = frame.origin.x + size.width / 2;
    CGFloat y = frame.origin.y + size.height / 2;
    CGPoint center = CGPointMake(x, y);
    
    // Draw eyes and smile
    CGSize eyeSize = CGSizeMake(frame.size.width * 0.1, frame.size.height * 0.1);
    CGFloat separation = frame.size.width * 0.1;
    
    CGPoint leftPt = CGPointMake(center.x - (separation + eyeSize.width),
                                 center.y - (eyeSize.height * 2));
    CGPoint rightPt = CGPointMake(center.x + separation,
                                  center.y - (eyeSize.height * 2));
    
    CGRect leftEye = CGRectMake(leftPt.x, rightPt.y, eyeSize.width, eyeSize.height);
    CGRect rightEye = CGRectMake(rightPt.x, rightPt.y, eyeSize.width, eyeSize.height);
    CGContextSetFillColorWithColor(context, [[UIColor blackColor] CGColor]);
    CGContextFillEllipseInRect(context, leftEye);
    CGContextFillEllipseInRect(context, rightEye);
    
    CGFloat smileHeight = center.y + eyeSize.height;
    CGPoint leftEdge = CGPointMake(leftEye.origin.x, smileHeight);
    CGPoint rightEdge = CGPointMake(rightEye.origin.x + rightEye.size.width, smileHeight);
    CGFloat smileLength = rightEdge.x - leftEdge.x;
    CGFloat smileWidth = eyeSize.width / 3;
    
    CGContextSetLineWidth(context, smileWidth);
    CGContextBeginPath(context);
    CGContextMoveToPoint(context, leftEdge.x, leftEdge.y);
    CGContextAddCurveToPoint(context, leftEdge.x + (smileLength / 4),
         smileHeight + smileWidth * 2, rightEdge.x - (smileLength / 4),
         smileHeight + smileWidth * 2, rightEdge.x, rightEdge.y);
    CGContextStrokePath(context);
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}
@end

Solved the problem! I hadn’t connected the UIImageView object to its swift code.