ios - UICollectionView 中的单元格随着水平滚动而消失

Question

我已经被这个奇怪的问题困扰了一段时间，似乎无法弄清楚。

设置

• A 是一个 UICollectionView
• B是 A 的 UICollectionViewCell

• C 是当用户点击 B 时作为 B 的 subview 添加的 UICollectionView

  +------------------------------+
  |A                             |
  |                              |
  | +----------+    +----------+ |
  | |B         |    |B         | |
  | |----------|    |          | |
  | |          |    |          | |
  | |C         |    |          | |
  | +----------+    +----------+ |
  +------------------------------+
  

问题

当将 C 的 UICollectionViewFlowLayout 滚动方向属性初始化为 .horizo​​ntal 时，并滚动经过第二个单元格，C 的细胞正在消失。

作为奖励，C 本身将从 UI 中消失:用户可以再次点击该单元格，该单元格将执行 C 常规删除时执行的所有操作。当再次点击以正常重新显示它时，会触发 C 显示时触发的操作，但在视觉上仍然找不到 C。

当滚动方向设置为 .vertical 时，不会出现此问题。

有人遇到过类似的问题或有任何关于这里发生的事情的线索吗？

提前致谢。

<小时/>

编辑实际实现

(B)

import UIKit

class CollectionViewCell: UICollectionViewCell {

    //...

    private let cellId = "cellId"

    private lazy var label: UILabel = {

        return CollectionViewCell._label()
    }()

    fileprivate lazy var gallery: UICollectionView = {

        return CollectionViewCell._gallery()
    }()

    //...

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

        isOpaque = true
        clipsToBounds = true
        layer.borderWidth = 1.5
        layer.cornerRadius = 8

        // ...
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    private func onSwitchDisplayGallery(_ isDiplaying: Bool) {

        switch isDiplaying {

        case true:

            addSubview(label)
            label.topAnchor.constraint(equalTo: topAnchor).isActive = true
            label.leftAnchor.constraint(equalTo: leftAnchor).isActive = true
            label.widthAnchor.constraint(equalTo: widthAnchor).isActive = true
            label.heightAnchor.constraint(equalToConstant: frame.height / 5.25).isActive = true

            gallery.register(NestedCollectionViewCell.self, forCellWithReuseIdentifier: cellId)
            gallery.delegate = self
            addSubview(gallery)
            gallery.topAnchor.constraint(equalTo: label.bottomAnchor).isActive = true
            gallery.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
            gallery.widthAnchor.constraint(equalTo: widthAnchor).isActive = true
            gallery.heightAnchor.constraint(equalTo: heightAnchor, constant: -frame.height / 5.25).isActive = true

        case false:

            print("removed cv")
            // ...
        }
    }

    //...
}

extension CollectionViewCell: UICollectionViewDelegateFlowLayout {

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

        return gallery.frame.size
    }
}


private extension CollectionViewCell {

    class func _gallery() -> UICollectionView {

        let layout = UICollectionViewFlowLayout()

        layout.minimumInteritemSpacing = 0
        layout.minimumLineSpacing = 0
        layout.scrollDirection = .horizontal

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

        cv.isPagingEnabled = true
        cv.showsHorizontalScrollIndicator = false
        cv.translatesAutoresizingMaskIntoConstraints = false
        return cv
    }

    class func _label() -> UILabel {

        let label = UILabel()

        label.font = UIFont(name: "Montserrat-Regular", size: 15)
        label.textColor = .white
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }
}

(C)

import UIKit

class NestedCollectionViewCell: UICollectionViewCell {

    private let containerView = NestedCollectionViewCell._containerView()

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

        isOpaque = true
        clipsToBounds = true
        backgroundColor = .white

        addSubview(containerView)
        containerView.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
        containerView.centerYAnchor.constraint(equalTo: centerYAnchor).isActive = true
        containerView.widthAnchor.constraint(equalTo: widthAnchor).isActive = true
        containerView.heightAnchor.constraint(equalTo: heightAnchor).isActive = true

        //...
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

private extension NestedCollectionViewCell {

    class func _containerView() -> UIImageView {

        let view = UIImageView()

        view.contentMode = .scaleAspectFill
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }
}

<小时/>

编辑2我已经尝试过尼克的回答here .

当滚动方向设置为.vertical时，一切正常。

当设置为.horizo​​ntal时，C不显示单元格...

Answer 1

愚蠢、愚蠢的菜鸟错误。如果其他人像我一样需要眼镜，请将其留在这里:)

Collection View 没有水平约束...

addSubview(gallery)
gallery.topAnchor.constraint(equalTo: label.bottomAnchor).isActive = true
gallery.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true

将其更正为

addSubview(gallery)
gallery.topAnchor.constraint(equalTo: label.bottomAnchor).isActive = true
gallery.leftAnchor.constraint(equalTo: leftAnchor).isActive = true

修复了它(显然)。