Swift: fatal error :在 dispatch_async dispatch_get_global_queue 中展开可选值时意外发现 nil

Question

我有一个表格 View ，其中我显示了 3 个单元格，并且取决于像分页一样工作的 Collection View 单元格。所以当我想从 dispatch_async(dispatch_get_global_queue...) 获取表格 View 单元格上的图像时，我得到了

fatal error: unexpectedly found nil while unwrapping an Optional value

我的代码是:

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    let cell = self.videoTableView .dequeueReusableCellWithIdentifier("customTableViewCell") as! CustomTableViewCell

    let videoDataObj:VideoData  = subVideoArray .objectAtIndex(indexPath.row) as! VideoData
    cell.titleLabel.text        = videoDataObj.videoTitle as String
    cell.descLabel.text         = videoDataObj.videoDesc  as String
    cell.playButton.tag         = indexPath.row + (pageIndex * noOfElement)

    let imageUrl =  NSURL(string: videoDataObj.videoImage as String)

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)){
        let data    =   NSData(contentsOfURL: imageUrl!)
        dispatch_async(dispatch_get_main_queue(), {

            cell.videoImageView?.contentMode = .ScaleToFill
            cell.videoImageView?.image   =   UIImage(data: data!)

            cell.setNeedsLayout()
            cell.layoutIfNeeded()
        })
        }

    return cell

}

View 的屏幕截图是:enter image description here提前致谢

Answer 1

是的!!!我检查了我的代码并得到了解决方案。我犯了一个愚蠢的错误。尝试一下..更新代码。

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)){

        if let data  = NSData(contentsOfURL: imageUrl!){
            dispatch_async(dispatch_get_main_queue(), {

                cell.videoImageView?.contentMode = .ScaleToFill
                cell.videoImageView?.image   =   UIImage(data: data)

                cell.setNeedsLayout()
                cell.layoutIfNeeded()
            })

        }