Issue with large navigation bar and collection view

SegmentedCollectionViewController.swift

import UIKit

class SegmentedControlSupplementaryView: UICollectionReusableView {
    let segmentControl = UISegmentedControl(items: ["Item 1", "Items 2", "Items 3"])
    static let reuseIdentifier = "segmented-supplementary-reuse-identifier"

    override init(frame: CGRect) {
        super.init(frame: frame)
        
        self.backgroundColor = .white
        configure()
    }
    
    required init?(coder: NSCoder) {
        fatalError()
    }
}

extension SegmentedControlSupplementaryView {
    func configure() {
        addSubview(segmentControl)
        segmentControl.translatesAutoresizingMaskIntoConstraints = false
        
        let inset = CGFloat(10)
        NSLayoutConstraint.activate([
            segmentControl.leadingAnchor.constraint(equalTo: leadingAnchor, constant: inset),
            segmentControl.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -inset),
            segmentControl.topAnchor.constraint(equalTo: topAnchor, constant: inset),
            segmentControl.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -inset)
        ])
        
        self.setNeedsLayout()
    }
}


let sectionHeaderElementKind = "sticky-header-element-kind"
let itemsPerPage = 15
let section = "Sticky Header"
let sectionHeader = "Section Header"

class StickyHeaderViewController: UIViewController {
    var dataSource: UICollectionViewDiffableDataSource<String, Int>? = nil
    var collectionView: UICollectionView?
    
    // initial data
    var items: [Int] = []
    var currentOffset: Int = 0
    
    fileprivate lazy var refreshControl: UIRefreshControl = {
        let refreshControl = UIRefreshControl()
        refreshControl.addTarget(self, action: #selector(performRefresh(_:)), for: UIControl.Event.valueChanged)
        return refreshControl
    }()
    
    /// A background serial queue is used to calculate diffing and apply snapshot to the registered collection view
    fileprivate let serialQueue = DispatchQueue(label: "assetlist.update.serial.queue")
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.view.backgroundColor = .white
        self.navigationController?.navigationBar.prefersLargeTitles = true
        self.navigationItem.title = "Sticky Section Headers"
        
        self.edgesForExtendedLayout = .all
        self.extendedLayoutIncludesOpaqueBars = true
        
        self.navigationItem.searchController = UISearchController()
        
        setUpNavBarAppearance()
        setUpCollectionView()
        configureDataSource()
    }
    
    func setUpNavBarAppearance() {
        let appearance = UINavigationBarAppearance()
        appearance.configureWithOpaqueBackground()
        appearance.backgroundColor = .white
        appearance.shadowColor = .clear

        self.navigationController?.navigationBar.standardAppearance = appearance
        self.navigationController?.navigationBar.scrollEdgeAppearance = appearance
    }

    func layout() -> UICollectionViewLayout {
        let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
                                             heightDimension: .fractionalHeight(1.0))
        let item = NSCollectionLayoutItem(layoutSize: itemSize)

        let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
                                              heightDimension: .absolute(44))
        let group = NSCollectionLayoutGroup.horizontal(layoutSize: groupSize, subitems: [item])

        let section = NSCollectionLayoutSection(group: group)
        section.interGroupSpacing = 5
        section.contentInsets = NSDirectionalEdgeInsets(top: 0, leading: 10, bottom: 0, trailing: 10)

        let sectionHeader = NSCollectionLayoutBoundarySupplementaryItem(
            layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
                                              heightDimension: .estimated(44)),
            elementKind: sectionHeaderElementKind,
            alignment: .top)
        sectionHeader.pinToVisibleBounds = true
        sectionHeader.zIndex = 2
        section.boundarySupplementaryItems = [sectionHeader]

        let layout = UICollectionViewCompositionalLayout(section: section)
        return layout
    }

    func setUpCollectionView() {
        let collectionView = UICollectionView(frame: self.view.bounds, collectionViewLayout: layout())
        collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        collectionView.backgroundColor = .systemBackground
        collectionView.delegate = self
        collectionView.register(ListCell.self, forCellWithReuseIdentifier: ListCell.reuseIdentifier)
        collectionView.register(SegmentedControlSupplementaryView.self,
                    forSupplementaryViewOfKind: sectionHeaderElementKind,
                    withReuseIdentifier: SegmentedControlSupplementaryView.reuseIdentifier)
        self.view.addSubview(collectionView)
        collectionView.refreshControl = refreshControl
        self.collectionView = collectionView
    }
    
    func configureDataSource() {
        guard let collectionView = self.collectionView else {
            return
        }
        
        dataSource = UICollectionViewDiffableDataSource<String, Int>(collectionView: collectionView) {
            (collectionView: UICollectionView, indexPath: IndexPath, identifier: Int) -> UICollectionViewCell? in

            // Get a cell of the desired kind.
            guard let cell = collectionView.dequeueReusableCell(
                withReuseIdentifier: ListCell.reuseIdentifier,
                for: indexPath) as? ListCell else { fatalError("Cannot create new cell") }

            // Populate the cell with our item description.
            cell.label.text = "\(indexPath.section),\(indexPath.item)"
            return cell
        }
        
        dataSource?.supplementaryViewProvider = { [weak self]
            (collectionView: UICollectionView, kind: String, indexPath: IndexPath) -> UICollectionReusableView? in

            // Get a supplementary view of the desired kind.
            guard let header = collectionView.dequeueReusableSupplementaryView(
                ofKind: kind,
                withReuseIdentifier: SegmentedControlSupplementaryView.reuseIdentifier,
                for: indexPath) as? SegmentedControlSupplementaryView else { fatalError("Cannot create new header") }

            header.segmentControl.addTarget(self, action: #selector(self?.segmentChanged), for: .valueChanged)
            
            // Return the view.
            return header
        }

        var snapshot = NSDiffableDataSourceSnapshot<String, Int>()
        snapshot.appendSections([section])
        items = Array(currentOffset..<currentOffset + 2*itemsPerPage)
        currentOffset += 2*itemsPerPage

        snapshot.appendItems(items)
        
        serialQueue.async { [weak self] in
            self?.dataSource?.apply(snapshot, animatingDifferences: true)
        }
    }
    
    @objc func segmentChanged() {
        self.collectionView?.setContentOffset(.zero, animated: true)
    }
    
    @objc
    func performRefresh(_ refreshControl: UIRefreshControl?) {
        getNextPage()
        
        // if not nil make sure to call end refreshing.
        DispatchQueue.main.async {
           refreshControl?.endRefreshing()
        }
    }
    
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        self.navigationController?.pushViewController(StickyHeaderViewController(), animated: true)
    }
}