ios - 在 collectionView 单元格上添加边框

Question

每次用户单击特定单元格时，该单元格都会有一个边框。问题是当我来回滚动时，边框正在选择随机单元格以具有边框。

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)
    cell?.layer.borderColor = UIColor.blue.cgColor
    cell?.layer.borderWidth = 1
}

以防万一你正在寻找 didDeselect 部分

func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)
    cell?.layer.borderColor = UIColor.clear.cgColor
    cell?.layer.borderWidth = 1
}

Answer 1

这是因为细胞的可重用性。您应该在您的单元格模型中使用属性来跟踪选定状态 - isSelected: Bool

现在在 cellForItem 方法中，如果 isSelected 为 true，则必须放置 if else 并使单元格有边框。

这里要注意的是，别忘记放else部分，去掉else部分的border。

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)
    cell?.layer.borderColor = UIColor.blue.cgColor
    cell?.layer.borderWidth = 1
    cell?.isSelected = true
}


func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
    let cell = collectionView.cellForItem(at: indexPath)
    cell?.layer.borderColor = UIColor.clear.cgColor
    cell?.layer.borderWidth = 1
    cell?.isSelected = false
}


override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
        ...
        ...
        if cell.isSelected {
            //put border logic
        }else {
            // remove border
        }
        return cell
    }