在 collectionView 单元格上添加边框

每次用户单击特定单元格时，该单元格都会有边框。问题是当我来回滚动时，边框会选择随机单元格来设置边框。

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

以防万一您正在寻找 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
}

这是因为细胞的可重复使用性。您应该在单元模型中获取属性来跟踪选定的状态 -isSelected: Bool

Now in cellForItem方法，你必须添加 if else 并使你的单元格有边框 ifisSelected is true.

这里请注意，不要忘记放置 else 部分并删除 else 部分中的边框。

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