iOS - 带有内容插入的粘性标题 - 标题 View 不像单元格那样滚动

Question

我们尝试像 map 上的列表一样滚动UICollectionView。不要将其与捕捉到某个点(如低、中和高)的底板混淆。 CollectionView 的 flowlayout 属性已启用 sectionHeadersPinToVisibleBounds。我附上了示例项目供您引用。当用户滚动时，有什么方法可以将标题 View 移动到 Collection View 的顶部吗？

Here是示例项目

我需要进行必要的改变才能进入这种状态:

let layout = UICollectionViewFlowLayout()
layout.sectionHeadersPinToVisibleBounds = true
layout.minimumLineSpacing = 0
layout.minimumInteritemSpacing = 0

let collectionView = UICollectionView(frame: .zero,
                                              collectionViewLayout: layout)


override func viewWillLayoutSubviews() {
  super.viewWillLayoutSubviews()

  collectionView.contentInset = UIEdgeInsets(top: drawerHeight, left: 0, bottom: 0, right: 0)
}

这是您将看到的屏幕截图:

红色 View 是固定的标题 View 。我是否需要自定义布局来在用户滚动时更新其位置？

Answer 1

我受此启发编写了一个自定义的 StickyHeaderLayout post 。这是我的错误的修复:

class StickyHeaderLayout: UICollectionViewFlowLayout {

    override init() {
        super.init()
        configureLayout()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        configureLayout()
    }

    private func configureLayout() {
        self.sectionFootersPinToVisibleBounds = true
        self.sectionHeadersPinToVisibleBounds = true
        minimumLineSpacing = 0
        minimumInteritemSpacing = 0
    }

    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        guard let attributes = super.layoutAttributesForElements(in: rect) else { return nil }

        for attribute in attributes {
            adjustAttributesIfNeeded(attribute)
        }
        return attributes
    }

    override func layoutAttributesForSupplementaryView(ofKind elementKind: String, at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        guard let attributes = super.layoutAttributesForSupplementaryView(ofKind: elementKind, at: indexPath) else { return nil }
        adjustAttributesIfNeeded(attributes)
        return attributes
    }

    func adjustAttributesIfNeeded(_ attributes: UICollectionViewLayoutAttributes) {
        switch attributes.representedElementKind {
        case UICollectionView.elementKindSectionHeader?:
            adjustHeaderAttributesIfNeeded(attributes)
        default:
            break
        }
    }

    private func adjustHeaderAttributesIfNeeded(_ attributes: UICollectionViewLayoutAttributes) {
        guard let collectionView = collectionView else { return }
        guard attributes.indexPath.section == 0 else { return }

        if collectionView.contentOffset.y <= 0 {
            attributes.frame.origin.y = 0
        } else {
            attributes.frame.origin.y = collectionView.contentOffset.y
        }
    }
}