ios - 使用属性观察器更改 Collection View 单元格是否不好？

Question

class SceneCell: UICollectionViewCell {

    override var isSelected: Bool {
        didSet {
            setSelected(bool: isSelected)
        }
    }

    override var isHighlighted: Bool {
        didSet {
            setHighlighted(bool: isHighlighted)
        }
    }

    @IBOutlet weak var thumbnailImageView: UIImageView!

    override func draw(_ rect: CGRect) {
        super.draw(rect)

        self.backgroundColor = .clear
        self.thumbnailImageView.layer.borderColor = UIColor.green.cgColor
        self.thumbnailImageView.layer.masksToBounds = true
        self.thumbnailImageView.clipsToBounds = true
        self.thumbnailImageView.layer.cornerRadius = 8
    }

    func update(with scene: Scene) {

    }

    private func setHighlighted(bool: Bool) {
        if bool {
            self.alpha = 0.5
        } else {
            self.alpha = 1.0
        }
    }

    private func setSelected(bool: Bool) {
        if bool {
            self.thumbnailImageView.layer.borderWidth = 2.5
        } else {
            self.thumbnailImageView.layer.borderWidth = 0
        }
    }
}

在我的代码中，当 isSelected 设置为 true 时，我将 ImageView 的图层边框宽度更改为 2.5。

当我选择一个单元格并滚动 Collection View 时，我认为在重用该选定单元格时单元格保持选定状态，但重用单元格会更改为未选定状态。其次，当我返回到选定的单元格并重新使用未选定的单元格时，我认为它处于未选定状态。但单元格会自动设置为选中状态。

Collection View 会自动管理这些吗？

Answer 1

问题的代码运行良好。这是记录单元格选择并应用选定/取消选定状态设置的替代解决方案。

class ViewController: UIViewController,UICollectionViewDelegate,UICollectionViewDataSource {
    //......

    var selectedIndexPaths = [IndexPath]()

    public func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        selectedIndexPaths.append(indexPath)
    }

    public func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
        if let index = selectedIndexPaths.index(of: indexPath) {
            selectedIndexPaths.remove(at: index)
        }
    }

    public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        //...
        cell.setSelected(selectedIndexPaths.contains(indexPath)) //Remember to make the cell's setSelected() public.
        //...
    }

    //......
}