HeroBannerViewController

Blog - Keep Hero Banner Floating in UIScrollView

import UIKit

class HeroBannerViewController: UIViewController, UIScrollViewDelegate {

    @IBOutlet var constraintHeroBannerHeight: NSLayoutConstraint!
    var defaultBannerHeight:CGFloat = 0
    var minimumBannerHeight:CGFloat = 0
    
    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        defaultBannerHeight = constraintHeroBannerHeight.constant
        minimumBannerHeight = 80
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        let offset = scrollView.contentOffset;
        if offset.y < minimumBannerHeight {
            constraintHeroBannerHeight.constant = defaultBannerHeight - offset.y
        }
    }
}