单元格随UICollectionView中的水平滚动消失

Question

我在这个奇怪的问题上停留了一段时间，似乎无法解决。

设定

• A是一个UICollectionView
• B是A的UICollectionViewCell

• C是当用户在B中轻UICollectionView添加为B的子视图的UICollectionView

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

问题

将C的UICollectionViewFlowLayout滚动方向属性初始化为.horizontal ， 并滚动经过第二个单元格时 ，C的单元格消失了。

随着奖金C本身从UI消失 ：用户再次能够点击该单元格，该单元格执行C常规删除操作所完成的所有动作。 当再次点按以正常重新显示它时，会触发C的显示触发的动作，但在视觉上仍找不到C。

当滚动方向设置为.vertical时，不会发生此问题。

有没有人遇到过类似的问题或关于这里发生情况的任何线索？

提前致谢。

---

编辑实际实施

（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
    }
}

---

编辑2我在这里尝试过尼克的答案。

当滚动方向设置为.vertical ，一切正常。

设置为.horizontal C时不显示任何单元格...

Answer 1

傻子，傻子菜鸟的错误。 如果有人像我一样需要眼镜，就把它留在这里：)

集合视图没有水平约束...

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

更正为

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

修复它（显然）。