Question

我试图在选择时更改单元格的backgorund颜色。但细胞背景颜色没有变化。

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CategoryCollectionViewCell
        let category = self.categories[indexPath.row]
        switch cell.isSelected {
        case true:
            cell.backgroundColor = .black
        default:
            cell.backgroundColor = .white
        }
        cell.setNeedsDisplay()


    }

Answer 1

选择后无需手动更改背景颜色。为此，UICollectionViewCell有一个名为selectedBackgroundView的属性。

在collectionView(_:cellForItemAt:)委托方法中使用它，如下所示：

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
}

Answer 2

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

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

Answer 3

您应该使用两个集合视图委托方法，如下所示：

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
}

Answer 4

在didSelect委托方法中尝试以下内容：

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

    selectedCell?.backgroundColor = UIColor.blueColor()
}

Answer 5

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

Answer 6

我认为通过观察单元格的属性 isSelected 来处理单元格的背景颜色应该是单元格的一部分。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选定的单元格会很棘手，例如：

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

UICollectionviewCell backgroundColor选中时不更改

6 个答案: