iOS:在uicollectionview中添加UIProgressView，以显示上传到firebase存储的上传百分比

   var progressView: UIProgressView!

   override init(frame: CGRect) {

       super.init(frame: frame)

       setupProgressView()

   }

   required init?(coder aDecoder: NSCoder) {

       super.init(coder: aDecoder)

       setupProgressView()

   }

   private func setupProgressView() {

       progressView = UIProgressView(progressViewStyle: .default)

       progressView.translatesAutoresizingMaskIntoConstraints = false

       contentView.addSubview(progressView)

       // 添加约束，根据需求设置UIProgressView的位置和大小

       NSLayoutConstraint.activate([

           progressView.leadingAnchor.constraint(equalTo: contentView.leadingAnchor),

           progressView.trailingAnchor.constraint(equalTo: contentView.trailingAnchor),

           progressView.bottomAnchor.constraint(equalTo: contentView.bottomAnchor),

           progressView.heightAnchor.constraint(equalToConstant: 5)

       ])

   }

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

   // 获取上传进度，这里假设有一个数组来保存每个UICollectionViewCell的上传进度

   let progress = uploadProgressArray[indexPath.item]

   // 更新UIProgressView的进度

   cell.progressView.progress = progress

   return cell

   // 上传完成后的处理

   guard let progress = snapshot.progress else { return }

   // 计算上传进度百分比

   let percentComplete = Float(progress.completedUnitCount) / Float(progress.totalUnitCount)

   // 更新uploadProgressArray中对应UICollectionViewCell的上传进度

   uploadProgressArray[indexPath.item] = percentComplete

   // 刷新UICollectionView以更新UIProgressView的显示

   collectionView.reloadItems(at: [indexPath])