SubViews don't scroll but scroll bar appears scrolling in swift

Question

I am creating scrollView programmatically, but for some reasons i can see the scrollView's scroll bar but the subViews aren't scrolling. Have added my codes below

//create a closure for scroll view
    let vcScrollView: UIScrollView = {
        let scrollView = UIScrollView()
        scrollView.translatesAutoresizingMaskIntoConstraints = false
        scrollView.backgroundColor = UIColor.dark_background

        return scrollView
    }()

//create closure for dark view
    let darkView: UIView = {
        let view = UIView()
        view.backgroundColor = UIColor.black
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()

//create a closure for offer label
    let offerLabel: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        label.textColor = UIColor.white
        return label
    }()

override func viewDidLoad() {
        super.viewDidLoad()
        modalPresentationCapturesStatusBarAppearance = true

        view.addSubview(vcScrollView)
        setUpViews()


    }

func setUpViews(){
        //scrollView
        vcScrollView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        vcScrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        vcScrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
        vcScrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        vcScrollView.contentSize.height = 1500

        //Dark view
        vcScrollView.addSubview(darkView)
        darkView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        darkView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        darkView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
        darkView.heightAnchor.constraint(equalToConstant: 130).isActive = true

        //Offer Label
        darkView.addSubview(offerLabel)
        offerLabel.text = selectedOffer
        offerLabel.font = UIFont(name: String.defaultFontR, size: 29)
        offerLabel.textAlignment = .center
        offerLabel.topAnchor.constraint(equalTo: darkView.topAnchor, constant: 95).isActive = true
        offerLabel.leadingAnchor.constraint(equalTo: darkView.leadingAnchor, constant: 20).isActive = true
        offerLabel.trailingAnchor.constraint(equalTo: darkView.trailingAnchor, constant: -20).isActive = true
    }

Have added the scroll view as a subView for the view too. Thanks in advance

Derek Derek · Accepted Answer · 2018-08-06T16:37:59

The problem is your child of the scroll view is using the view's anchors. Switch them to use the scrollView's anchors. Also, instead of a trailing constraint, you can use a width constraint. That will allow it to scroll up and down.

//Dark view
vcScrollView.addSubview(darkView)
darkView.leadingAnchor.constraint(equalTo: vcScrollView.leadingAnchor).isActive = true
darkView.topAnchor.constraint(equalTo: vcScrollView.topAnchor).isActive = true
darkView.widthAnchor.constraint(equalTo: vcScrollView.widthAnchor).isActive = true
darkView.heightAnchor.constraint(equalToConstant: 130).isActive = true

You will need to provide the bottom anchors of your child views if you want to include views under your darkView.

SubViews don't scroll but scroll bar appears scrolling in swift

2 Answers