的iOS - 的CollectionView图像消失上滚动和有时重叠

Question

当从服务器下载图像和填充集合视图（电网3 * N）。我正在发生故障。

我几乎尝试了一切可能像重用细胞，并使用GCD从主线程更新图像视图之前使图像视图为零。

但我仍然面临着小故障。

毛刺是，当我滚动集合视图，下载重叠，有时图像从集合视图细胞消失。

我不知道是什么原因造成的图像消失（这曾经下载）。

任何建议。

private func cellForDropbox(cell:GridCell,indexPath:IndexPath) -> GridCell { 

    let filename = self.filenames[(indexPath as NSIndexPath).row] 

    cell.imageView.backgroundColor = UIColor.lightGray 
    cell.imageView.image = nil 

    DropboxClientsManager.authorizedClient?.files.getTemporaryLink(path: filename).response(completionHandler: { (response, error) in 

      if let url = response { 
       cell.imageView.sd_setImage(with: URL(string:url.link), placeholderImage: nil, options: .refreshCached, completed: { (img, error, cacheType, url) in 
       }) 

      } else { 
       print("Error downloading file from Dropbox: \(error!)") 
      } 
     }) 

    return cell 
} 

Answer 1

如果不想完成图像下载回调，请尝试此操作。

private func cellForDropbox(cell:GridCell,indexPath:IndexPath) -> GridCell { 

    let filename = self.filenames[(indexPath as NSIndexPath).row] 

    cell.imageView.backgroundColor = UIColor.lightGray 

    DropboxClientsManager.authorizedClient?.files.getTemporaryLink(path: filename).response(completionHandler: { (response, error) in 

      if let url = response { 
      cell.imageView.sd_setImage(with: URL(string: url.link), placeholderImage: UIImage(named: "placeholder.png")) 


      } else { 
       print("Error downloading file from Dropbox: \(error!)") 
      } 
     }) 

    return cell 
}