UIScrollEdgeElementContainerInteraction test

ContentView.swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        // 1: Not nested in NC
        ListVCRepresentable()
            .ignoresSafeArea()

        // 2: Nested in NC
//        NavigationStack {
//            ListVCRepresentable()
//                .ignoresSafeArea()
//                .navigationTitle("Home")
//                .navigationBarTitleDisplayMode(.inline)
//        }
    }
}

struct ListVCRepresentable: UIViewControllerRepresentable {
    func makeUIViewController(context: Context) -> some UIViewController {
        ListVC(collectionViewLayout: UICollectionViewCompositionalLayout.list(using: .init(appearance: .insetGrouped)))
    }

    func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
    }
}

final class ListVC: UICollectionViewController {
    @ViewLoading var dataSource: UICollectionViewDiffableDataSource<Int, Int>

    override func viewDidLoad() {
        super.viewDidLoad()

        let registration = UICollectionView.CellRegistration<UICollectionViewListCell, Int> { cell, indexPath, item in
            cell.contentConfiguration = UIHostingConfiguration {
                Color.purple.frame(width: 100, height: 100)
            }
        }

        dataSource = .init(collectionView: collectionView) { collectionView, indexPath, itemIdentifier in
            collectionView.dequeueConfiguredReusableCell(using: registration, for: indexPath, item: itemIdentifier)
        }

        var snapshot = NSDiffableDataSourceSnapshot<Int, Int>()
        snapshot.appendSections([0])
        snapshot.appendItems((0...100).map { $0 })
        dataSource.apply(snapshot)

        collectionView.topEdgeEffect.style = .hard

        let header = UIView()
        let interaction = UIScrollEdgeElementContainerInteraction()
        interaction.edge = .top
        interaction.scrollView = collectionView
        header.addInteraction(interaction)

        var buttonConfig = UIButton.Configuration.borderedProminent()
        buttonConfig.title = "Button"
        let button = UIButton(configuration: buttonConfig)

        view.addSubview(header)
        header.addSubview(button)

        header.translatesAutoresizingMaskIntoConstraints = false
        button.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            header.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            header.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            header.topAnchor.constraint(equalTo: view.topAnchor),

            button.topAnchor.constraint(equalTo: header.safeAreaLayoutGuide.topAnchor),
            button.leadingAnchor.constraint(equalTo: header.leadingAnchor, constant: 16),

            header.bottomAnchor.constraint(equalTo: button.bottomAnchor, constant: 16),
        ])
    }
}

#Preview {
    ContentView()
}