如何动态更改UICollectionView镜像的borderColor

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CellIdentifier", for: indexPath) as! UICollectionViewCell
    
    // 设置边框颜色
    cell.layer.borderColor = UIColor.red.cgColor
    
    return cell
}

// 定义边框颜色变量
var borderColor = UIColor.red.cgColor

// 更改边框颜色的方法
func changeBorderColor() {
    borderColor = UIColor.blue.cgColor
    collectionView.reloadData()
}

// 在代理方法中设置边框颜色
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CellIdentifier", for: indexPath) as! UICollectionViewCell
    
    // 设置边框颜色
    cell.layer.borderColor = borderColor
    
    return cell
}