尝试创建效果，使集合视图在滚动时滑过另一个集合视图

Question

我有两个集合视图，在ViewController中一个在另一个视图之上。顶部的集合视图是水平滚动的集合视图，而下面的一个则垂直滚动。我正在尝试创建一种效果，其中滚动下部的收藏夹视图将导致其向上移动以覆盖上部的收藏夹视图，就像一种视差效果一样。

我设法通过将两个视图固定在屏幕顶部并在滚动时修改下部集合视图的内容插图来获得效果，但是这种方法意味着即使上部集合视图暴露了，我也无法与之交互。我正在寻找对此方法的修改或新方法，以使我能够保留这种效果以及与上层集合视图进行交互。关于如何解决这个问题有什么建议吗？谢谢。

我目前拥有的代码（或多或少）：

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    scrollView.contentInset.top = max(0, min(tendToSoon.frame.height, -scrollView.contentOffset.y))
}

Gif example

未滚动：

轻微滚动：

更多滚动内容：

Answer 1

在视图控制器中添加两个collectionview，并将contentInset.top设置为第一个colletionview的高度。然后contentOffset.y减去contentInset.top的值。然后override point(inside:with:)并仅在y值大于0时返回true。

确保第二个collectionview的背景色是透明的。

class ViewController: UIViewController {

    let topCollectionTitle = UILabel()
    let topCollectionView = UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewLayout())
    let bottomCollectionView = BottomCollectionView(frame: .zero, collectionViewLayout: UICollectionViewLayout())

    override func viewDidLoad() {
        super.viewDidLoad()

        self.view.backgroundColor = .white

        topCollectionTitle.textAlignment = .center
        topCollectionTitle.text = "Top Collectionview"
        topCollectionTitle.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(topCollectionTitle)

        let topLayout = UICollectionViewFlowLayout()
        topLayout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
        topLayout.itemSize = CGSize(width: self.view.bounds.width / 5, height: 150)
        topLayout.scrollDirection = .horizontal
        topLayout.minimumLineSpacing = 0
        topLayout.minimumInteritemSpacing = 0
        topCollectionView.contentInsetAdjustmentBehavior = .never
        topCollectionView.collectionViewLayout = topLayout
        topCollectionView.backgroundColor = .white
        topCollectionView.register(CellHeader.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "CellHeader")

        topCollectionView.register(ImgCell.self, forCellWithReuseIdentifier: "ImgCell")
        topCollectionView.delegate = self
        topCollectionView.dataSource = self
        topCollectionView.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(topCollectionView)

        let bottomLayout = UICollectionViewFlowLayout()
        bottomLayout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
        bottomLayout.itemSize = CGSize(width: self.view.bounds.width / 2, height: 150)
        bottomLayout.scrollDirection = .vertical
        bottomLayout.minimumLineSpacing = 0
        bottomLayout.minimumInteritemSpacing = 0
        bottomLayout.headerReferenceSize = CGSize(width: 50, height: 50)
        bottomCollectionView.collectionViewLayout = bottomLayout
        bottomCollectionView.backgroundColor = .clear
        bottomCollectionView.register(CellHeader.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "CellHeader")
        bottomCollectionView.register(ImgCell.self, forCellWithReuseIdentifier: "ImgCell")
        bottomCollectionView.delegate = self
        bottomCollectionView.dataSource = self
        bottomCollectionView.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(bottomCollectionView)

        bottomCollectionView.contentInset.top = 200
        bottomCollectionView.contentOffset.y = -200

        topCollectionTitle.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor).isActive = true

        self.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[topCollectionView]|", options: [], metrics: nil, views: ["topCollectionView":topCollectionView]))
        self.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:[topCollectionTitle(30)][topCollectionView(200)]", options: [], metrics: nil, views: ["topCollectionView":topCollectionView,"topCollectionTitle":topCollectionTitle]))
        self.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-(10)-[topCollectionTitle]|", options: [], metrics: nil, views: ["topCollectionTitle":topCollectionTitle]))
        self.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[bottomCollectionView]|", options: [], metrics: nil, views: ["bottomCollectionView":bottomCollectionView]))
        self.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[bottomCollectionView]|", options: [], metrics: nil, views: ["bottomCollectionView":bottomCollectionView]))

    }
}
extension ViewController: UICollectionViewDelegate {

}
extension ViewController: UICollectionViewDataSource {
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 25
    }
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ImgCell", for: indexPath) as? ImgCell ?? ImgCell()
        cell.imgView.backgroundColor = .red
        return cell
    }
    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        if kind == UICollectionView.elementKindSectionHeader {
            let header = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "CellHeader", for: indexPath) as? CellHeader
            if collectionView == bottomCollectionView {
                header?.titleLbl.text = "Bottom CollectionView"
            }
            return header!
        }
        return UICollectionReusableView()
    }
}

class ImgCell: UICollectionViewCell {

    let imgView = UIImageView()

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupViews()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupViews()
    }
    func setupViews() {
        backgroundColor = .white

        imgView.layer.cornerRadius = 5.0
        imgView.layer.masksToBounds = true
        imgView.translatesAutoresizingMaskIntoConstraints = false
        addSubview(imgView)
        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-(5)-[imgView]-(5)-|", options: [], metrics: nil, views: ["imgView":imgView]))
        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-(5)-[imgView]-(5)-|", options: [], metrics: nil, views: ["imgView":imgView]))
    }
}
class CellHeader: UICollectionReusableView {

    let titleLbl = UILabel()

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupViews()
    }
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupViews()
    }
    func setupViews() {
        backgroundColor = .white

        titleLbl.textAlignment = .center
        titleLbl.translatesAutoresizingMaskIntoConstraints = false
        addSubview(titleLbl)

        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[titleLbl]|", options: [], metrics: nil, views: ["titleLbl":titleLbl]))
        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[titleLbl]|", options: [], metrics: nil, views: ["titleLbl":titleLbl]))
    }
}
class BottomCollectionView:UICollectionView {
    override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
        return point.y > 0
    }
}

Answer 2

• 将两个集合视图放在一个分数视图中并尝试生成并行效果，就可以实现这种效果。请在下面找到链接以供参考。

Source

将标头图片替换为您的收藏夹视图。