Working code fails when imported into project - ios

Question

I have a Scroll View tutorial that I customized to download images, rather than using local.
The project works fine. When I import the two files and two corresponding View Controllers into my main project it crashes. I'm getting the error
unexpectedly found nil while unwrapping an Optional value.
I've set break points throughout the project, also set exception breakpoint, but can't locate the issue. The Scroll View presents the first image then bombs.
First VC:
import UIKit
import Alamofire
import AlamofireImage
class TutorialViewController: UIViewController {
#IBOutlet weak var scrollView: UIScrollView!
#IBOutlet weak var pageControl: UIPageControl!
#IBOutlet weak var activityIndicator: UIActivityIndicatorView!
var pages = [TutorialStepViewController]()
var stringURLS: [String] = []
var networkStatus = NetworkStatus.searching
var constraintString = ""
enum NetworkStatus {
case searching
case finishedSearching
}
override func viewDidLoad() {
super.viewDidLoad()
scrollView.isPagingEnabled = true
getBrewerHistory(portalID: "7", galleryName: "Brewer History")
activityIndicator.startAnimating()
}
func configureScrollView() {
for i in 0..<stringURLS.count {
let page = createAndAddTutorialStep(stringURLS[i], iconImageName: "", text: "")
pages.append(page)
}
pageControl.numberOfPages = pages.count
var views: [String: UIView] = ["view": view]
for i in 0..<pages.count {
views.updateValue(pages[i].view, forKey: "page" + String(i))
}
let metrics = ["edgeMargin": 10, "betweenMargin": 20]
let verticalConstraints =
NSLayoutConstraint.constraints(
withVisualFormat: "V:|[page0(==view)]|", options: [], metrics: nil, views: views)
NSLayoutConstraint.activate(verticalConstraints)
for page in 0..<pages.count {
switch page {
case 0:
constraintString += "H:|-edgeMargin-[page" + String(page) + "(==view)]-betweenMargin-"
case pages.count-1:
constraintString += "[page" + String(page) + "(==view)]-edgeMargin-|"
default:
constraintString += "[page" + String(page) + "(==view)]-betweenMargin-"
}
}
let horizontalConstraints =
NSLayoutConstraint.constraints(
withVisualFormat: constraintString, options: [.alignAllTop, .alignAllBottom], metrics: metrics, views: views)
NSLayoutConstraint.activate(horizontalConstraints)
}
fileprivate func createAndAddTutorialStep(_ stringURL: String, iconImageName: String, text: String) -> TutorialStepViewController {
let tutorialStep = storyboard!.instantiateViewController(withIdentifier: "TutorialStepViewController") as! TutorialStepViewController
tutorialStep.view.translatesAutoresizingMaskIntoConstraints = false
let stringURL = stringURL
// tutorialStep.backgroundImage = UIImage(named: backgroundImageName)
let imageURL = URL(string: stringURL)
tutorialStep.backgroundImageURL = imageURL
tutorialStep.iconImage = UIImage(named: iconImageName)
tutorialStep.text = text
scrollView.addSubview(tutorialStep.view)
addChildViewController(tutorialStep)
tutorialStep.didMove(toParentViewController: self)
return tutorialStep
}
}
extension TutorialViewController: UIScrollViewDelegate {
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let pageWidth = scrollView.bounds.width
let pageFraction = scrollView.contentOffset.x / pageWidth
pageControl.currentPage = Int(round(pageFraction))
}
}
//Mark: Networking Calls
extension TutorialViewController {
func getBrewerHistory (portalID: String, galleryName: String) {
networkStatus = .searching
activityIndicator.isHidden = false
activityIndicator.startAnimating()
let apiURL = "http://www.smarttapp.com/DesktopModules/DnnSharp/DnnApiEndpoint/Api.ashx?method=GetBrewerHistory"
let params = ["PortalID" : portalID,
"GalleryName" : galleryName
]
Alamofire.request(
apiURL,
method: .get,
parameters: params
)
.responseJSON { response in
guard response.result.isSuccess else {
print("Error while fetching JSON: \(String(describing: response.result.error))")
return
}
guard let responseArray = response.result.value as? [NSDictionary] else { return }
for dict in responseArray {
if let url = dict["fileName"] as? String {
let fullURL = "http://www.smarttapp.com" + url
self.stringURLS.append(fullURL)
}
}
DispatchQueue.main.async {
self.activityIndicator.stopAnimating()
self.activityIndicator.isHidden = true
self.networkStatus = .finishedSearching
self.configureScrollView()
}
}
}
}
Second VC:
import UIKit
class TutorialStepViewController: UIViewController {
#IBOutlet fileprivate weak var backgroundImageView: UIImageView!
#IBOutlet fileprivate weak var iconImageView: UIImageView!
#IBOutlet fileprivate weak var textLabel: UILabel!
var backgroundImage: UIImage?
var backgroundImageURL: URL?
var iconImage: UIImage?
var text: String?
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
backgroundImageView.af_setImage(withURL: backgroundImageURL!)
iconImageView.image = iconImage
if let text = text {
let font = UIFont(name: "HelveticaNeue-Light", size:20.0)!
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = 8
paragraphStyle.alignment = .center
textLabel.attributedText = NSAttributedString(string: text,
attributes: [NSFontAttributeName: font, NSParagraphStyleAttributeName: paragraphStyle])
}
}
}