UIScrollview doesn't work once subviews added - swift

Question

I'm new to working with ScrollViews, and I'm doing it all programatically. I must be missing something super simple, but when I have no subviews, the scrollview shows up properly and scrolls up and down. But any time I add any subviews, the whole thing refuses to show up at all.
class DetailedPostScrollView: UIScrollView {
let topLabel: UILabel = {
let label = UILabel()
label.text = "this is the top"
return label
}()
let bottomLabel: UILabel = {
let label = UILabel()
label.text = "this is the bottom"
return label
}()
override init(frame: CGRect) {
super.init(frame: frame)
contentSize = CGSize(width: frame.width, height: 2000)
alwaysBounceVertical = true
addSubviewUsingAutoLayout(topLabel, bottomLabel)
topLabel.centerXAnchor.constrain(to: self.centerXAnchor)
topLabel.widthAnchor.constrain(to: 200)
topLabel.heightAnchor.constrain(to: 50)
topLabel.topAnchor.constrain(to: self.topAnchor, with: 100)
bottomLabel.centerXAnchor.constrain(to: self.centerXAnchor)
bottomLabel.widthAnchor.constrain(to: 200)
bottomLabel.heightAnchor.constrain(to: 50)
bottomLabel.bottomAnchor.constrain(to: self.bottomAnchor)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
And in my viewController, I instantiate and add the scroll view
let detailedPostScrollView = DetailedPostScrollView(frame: UIScreen.main.bounds)
detailedPostScrollView.backgroundColor = UIColor.purple
view.addSubviewUsingAutoLayout(detailedPostScrollView)
Again, I"m sure it's something super simple but I checked out all the questions and tutorial videos and couldn't see where I"m going wrong. Thanks for your help.
Edit: It seems to work fine when I do it all programmatically from a viewcontroller, as follows :
let scrollView: UIScrollView = {
let sv = UIScrollView()
sv.contentSize = CGSize(width: view.frame.width, height: 2000)
sv.backgroundColor = UIColor.purple
return sv
}()
view.addSubviewUsingAutoLayout(scrollView)
scrollView.topAnchor.constrain(to: view.topAnchor, with: 100)
scrollView.leadingAnchor.constrain(to: view.leadingAnchor)
scrollView.trailingAnchor.constrain(to: view.trailingAnchor)
scrollView.bottomAnchor.constrain(to: view.bottomAnchor)
let topLabel: UILabel = {
let label = UILabel()
label.text = "this is the top"
return label
}()
scrollView.addSubviewUsingAutoLayout(topLabel)
topLabel.centerXAnchor.constrain(to: scrollView.centerXAnchor)
topLabel.widthAnchor.constrain(to: 200)
topLabel.heightAnchor.constrain(to: 50)
topLabel.topAnchor.constrain(to: scrollView.topAnchor)
Something is off when I create a custom scrollview and instantiate that in my vc.

Answer 1

Try this :
class ViewController : UIViewController , UIScrollViewDelegate{
var scrollView : UIScrollView! ;
var containerView = UIView();
var contentSize : CGSize {
get {
return CGSize(width: view.frame.width, height: 2000);
}
}
override func viewDidLoad() {
super.viewDidLoad();
setupScrollView();
setupItems();
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews();
self.scrollView.frame = self.view.bounds;
containerView.frame = CGRect(x: 0, y: 0, width: contentSize.width, height: contentSize.height);
}
private func setupScrollView() {
scrollView = UIScrollView();
scrollView.delegate = self;
scrollView.backgroundColor = .white;
scrollView.contentSize = contentSize;
self.view.addSubview(scrollView);
containerView.backgroundColor = .purple;
self.scrollView.addSubview(containerView);
}
private func setupItems() {
let topButton = UIButton();
topButton.translatesAutoresizingMaskIntoConstraints = false;
topButton.setTitle("TOP BUTTON", for: .normal);
topButton.setTitleColor(.white, for: .normal);
self.containerView.addSubview(topButton);
let bottomTextField = UITextField();
bottomTextField.translatesAutoresizingMaskIntoConstraints = false;
bottomTextField.borderStyle = .roundedRect;
bottomTextField.placeholder = "BOTTOM TEXT FIELD";
self.containerView.addSubview(bottomTextField);
topButton.centerXAnchor.constraint(equalTo: containerView.centerXAnchor).isActive = true;
topButton.topAnchor.constraint(equalTo: containerView.topAnchor, constant: 50).isActive = true;
topButton.widthAnchor.constraint(equalToConstant: 100).isActive = true;
topButton.heightAnchor.constraint(equalToConstant: 50).isActive = true;
bottomTextField.centerXAnchor.constraint(equalTo: containerView.centerXAnchor).isActive = true;
bottomTextField.bottomAnchor.constraint(equalTo: containerView.bottomAnchor, constant: -50).isActive = true;
bottomTextField.widthAnchor.constraint(equalToConstant: 200).isActive = true;
bottomTextField.heightAnchor.constraint(equalToConstant: 40).isActive = true;
}
}
Set the scroll view frame to view bound in viewDidLayoutViews instead of using the layout , and add a container view as a subview for scroll view and set the size to same content size for scroll view again in viewDidLayoutViews so when ever user rotate the phone he get the correct width , and finally add all your views to container view .