ios - 在 UICollectionViewController 中仅选择一项

Question

我已经实现了 UICollectionViewController 的一个子类，它可以水平滚动，我希望它一次只能选择一个项目。

当我在当前屏幕上更改所选项目时，它工作正常。但是，例如，如果我在集合的最开头选择一个项目，然后向右滚动并选择另一个项目，第一个项目仍将被选中。

这是我的 CollectionView 的当前版本:

class GenresCollectionVC: UICollectionViewController {

    var selectedIndexPath: IndexPath?

    // MARK: UICollectionViewDataSource
    override func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }

    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return MockData.instance.genres.count
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(
            withReuseIdentifier: reuseIdentifier, for: indexPath) as! GenreCollectionViewCell

        cell.genreNameLabel.text = MockData.instance.genres[indexPath.row]
        if selectedIndexPath == indexPath {
            redraw(selectedCell: cell)
        } else {
            redraw(deselectedCell: cell)
        }

        return cell
    }

    // MARK: UICollectionViewDelegate
    override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        guard let cell = collectionView.cellForItem(at: indexPath) as? GenreCollectionViewCell else {
            return
        }
        redraw(selectedCell: cell)
        selectedIndexPath = indexPath
    }

    override func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
        guard let cell = collectionView.cellForItem(at: indexPath) as? GenreCollectionViewCell else {
            return
        }
        redraw(deselectedCell: cell)
        selectedIndexPath = nil
    }

    private func redraw(selectedCell cell: GenreCollectionViewCell
        ) {
        cell.layer.borderWidth = 1.0
        cell.layer.cornerRadius = cell.bounds.height / 2
        cell.layer.borderColor = UIColor.violetNeeoColor.cgColor

        cell.genreNameLabel.textColor = UIColor.violetNeeoColor
    }

    private func redraw(deselectedCell cell: GenreCollectionViewCell) {
        cell.layer.borderWidth = 0.0
        cell.layer.cornerRadius = 0.0

        cell.genreNameLabel.textColor = UIColor.white
    }
}

我做错了什么？

Answer 1

在您的 GenreCollectionViewCell 类中，覆盖 isSelected 属性，即

override var isSelected: Bool{
    willSet{
        super.isSelected = newValue
        if newValue
        {
            self.layer.borderWidth = 1.0
            self.layer.cornerRadius = self.bounds.height / 2
            self.layer.borderColor = UIColor.violetNeeoColor.cgColor
            self.genreNameLabel.textColor = UIColor.violetNeeoColor
        }
        else
        {
            self.layer.borderWidth = 0.0
            self.layer.cornerRadius = 0.0
            self.genreNameLabel.textColor = UIColor.white
        }
    }
}

现在您不需要在 didSelectItemAt delegate 方法中手动选择/取消选择单元格。 isSelected 属性将自动处理它。