UICollectionviewCell背景色在选中时不更改

您不需要在选择时手动更改背景颜色。UICollectionViewCell有一个名为 selectedBackgroundView 正是为了这个目的。

collectionView(_:cellForItemAt:) 委托方法如下:

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CategoryCollectionViewCell

    cell.selectedBackgroundView = UIView(frame: cell.bounds)
    cell.selectedBackgroundView!.backgroundColor = .black

    return cell
}

在您的didSelect委托方法中尝试以下操作:

override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
    let selectedCell = collectionView.cellForItemAtIndexPath(indexPath)

    selectedCell?.backgroundColor = UIColor.blueColor()
}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

    if let cell = collectionView.cellForItem(at: indexPath) {
        cell.backgroundColor = cell.isSelected ? .black : .white
    }
}

您应该使用以下两种集合视图委托方法:

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

  let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CategoryCollectionViewCell

  cell.backgroundColor = .black
}

和

func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {

  let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CategoryCollectionViewCell

  cell.backgroundColor = .white
}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    
    let cell = collectionView.cellForItem(at: indexPath) as! CustomCell
    cell.cellView.backgroundColor = .red
    
}

我认为通过观察细胞的特性,处理细胞的背景颜色应该是细胞的一部分 isSelected 它处理单元格的选择和取消选择,否则在选择任何其他单元格时取消选择所选单元格会很棘手,例如:

class MyCustomCollectionViewCell: UICollectionViewCell {
    override var isSelected: Bool {
        didSet {
            contentView.backgroundColor = isSelected ? .red : .white
        }
    }
}