ScrollView not reloading upon dismissing ViewController and calling viewDidLoad - swift

Question

I have a scrollView that contains a dynamic amount of WeatherViewControllers each displaying the weather data of a different city the user has saved. The user can segue from the WeatherViewControllers to a CityListViewController. Where they can add and remove cities from their list which in turn should add and remove WeatherViewControllers from the scrollView upon dismissing the CityListViewController, this is where I am running into a problem.
Currently I am using a protocol to call viewDidLoad in the scrollViewController upon dismissing the CityListViewController which works as I follow the code with the debugger all of the code that should be getting called is and the variable which tracks how many viewControllers to create is accurate after the change, however the scrollView is not changing. If I add/remove a city from the list the scrollView still displays the same amount as before.
The func createAndAddWeatherScreen is called the accurate amount of times after the change and everything and if I close the app and reopen it the scrollView then displays the right amount of viewControllers. It seems like everything is working except the scrollView is not reloading upon dismissing the cityListController.
Side Note: Upon initially opening the app the scrollView loads properly with all the correct WeatherViewControllers in the UIScrollView and the correct cities in the list.
class ScrollViewController: UIViewController, ScrollReloadProtocol {
func reloadScrollView() {
self.viewDidLoad()
}
//#IBOutlet var totalScrollView: UIScrollView!
var pages = [ViewController]()
var x = 0
var weatherScreensArray = [SavedCityEntity]()
var weatherScreenStringArray = [String]()
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
var horizString = "H:|[page1(==view)]"
let defaults = UserDefaults.standard
let scrollView: UIScrollView = {
let scrollView = UIScrollView()
scrollView.translatesAutoresizingMaskIntoConstraints = false
scrollView.isPagingEnabled = true
return scrollView
}()
override func viewDidLoad() {
super.viewDidLoad()
scrollView.delegate = self
view = scrollView
//userDefaults used to keep track of which screen is which to put different cities on different viewControllers
defaults.set(0, forKey: "screenNumber")
//load cities to get number of cities saved
loadCities()
var views : [String: UIView] = ["view": view]
//create all weatherWeatherControllers
while x <= weatherScreensArray.count {
pages.append(createAndAddWeatherScreen(number: x))
weatherScreenStringArray.append("page\(x+1)")
views["\(weatherScreenStringArray[x])"] = pages[x].view
let addToHoriz = "[\(weatherScreenStringArray[x])(==view)]"
horizString.append(addToHoriz)
x+=1
}
horizString.append("|")
let verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:|[page1(==view)]|", options: [], metrics: nil, views: views)
let horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: horizString, options: [.alignAllTop, .alignAllBottom], metrics: nil, views: views)
NSLayoutConstraint.activate(verticalConstraints + horizontalConstraints)
}
//Function to create and add weatherViewController
func createAndAddWeatherScreen(number: Int) -> ViewController {
defaults.set(number, forKey: "screenNumber")
let story = UIStoryboard(name: "Main", bundle: nil)
let weatherScreen = story.instantiateViewController(identifier: "View Controller") as! ViewController
weatherScreen.view.translatesAutoresizingMaskIntoConstraints = false
scrollView.addSubview(weatherScreen.view)
addChild(weatherScreen)
weatherScreen.didMove(toParent: self)
return weatherScreen
}

Answer 1

There are several architectural issues with your code:
You should not be calling the viewDidLoad method manually, it's very easy to extract the necessary code for fetching and reloading into a method of its own which doesn't break the lifecycle of a viewController.
It looks like you're attempting to use the scrollView as a tableView which offers reloading as a free function, as well as far better memory management.
You could use .map() instead of using while to iterate and create new arrays manually, higher order functions are very useful.
Despite all that, you can't actually reload a scrollView in the way you can a tableView. It already contains the views you added there previously, and it looks to me like you're stacking extra views over and over again, you could debug if this is the case with the visual debugger.
Lastly, in order to update a view after updating constraints you need to call:
setNeedsLayout()
layoutIfNeeded()
to let the system know you want to update the subviews and their layout.