iOS swift UICollectionviewcell 快照错误

Posted 2023-02-23

【中文标题】iOS swift UICollectionviewcell 快照错误

【英文标题】：iOS swift UICollectionviewcell snapshot error

【发布时间】：2017-04-20 07:25:39

【问题描述】：

当我尝试在 UICollectionview 中拍摄某个 UICollectionViewCell 的快照时，该 UICollectionViewCell 是 View 的子视图，并从我的应用程序在 Facebook 上分享它......而 Xcode 抛出

致命错误：在展开可选值时意外发现 nil

please click here for screenshot of that error

这是我的功能

func screenshotBSCell() 
        //Create the UIImage

        UIGraphicsBeginImageContext(CGSizeMake(bsCell.bounds.size.width, bsCell.bounds.size.height))
        ***self.bsCell.layer.renderInContext(UIGraphicsGetCurrentContext()!)***
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        //Save it to the camera roll
        UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)

        //share the image to Social Media
        let composeSheet = SLComposeViewController(forServiceType: SLServiceTypeFacebook)
        composeSheet.setInitialText("Hello, Facebook!")
        composeSheet.addImage(image)

        presentViewController(composeSheet, animated: true, completion: nil)

    

【问题讨论】：

调试并检查 self.bsCell 实例，是 nil 吗？

应用程序在 self.bsCell.layer.renderInContext((UIGraphicsGetCurrentContext())!) 行崩溃

你在哪里打电话给screenshotBSCell？问题是UIGraphicsGetCurrentContext() 返回 nil，然后您尝试强制解包（不要这样做:)）导致崩溃。所以...看来您对UIGraphicsBeginImageContext 的呼叫没有按预期工作。正如@Surjeet 建议的那样...验证您的bsCell 不为零，并检查bsCell 的大小以确保它有效。

我在 cellForItemAtIndexPath 内调用 cell.shareBtn.addTarget(self, action: #selector(screenshotBSCell), forControlEvents: .TouchUpInside)

【参考方案1】：

func screenshotBSCell( sender:AnyObject) 
        //Create the UIImage
        let indexpath = NSIndexPath.init(row: sender.tag, section: 0)

        self.bsCell = colletctionview!.dequeueReusableCellWithReuseIdentifier("cell", forIndexPath: indexPath ) as! bsCell
        UIGraphicsBeginImageContext(CGSizeMake(cell.bounds.size.width, cell.bounds.size.height))
        ***self.bsCell.layer.renderInContext(UIGraphicsGetCurrentContext()!)***
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        //Save it to the camera roll
        UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)

        //share the image to Social Media
        let composeSheet = SLComposeViewController(forServiceType: SLServiceTypeFacebook)
        composeSheet.setInitialText("Hello, Facebook!")
        composeSheet.addImage(image)

        presentViewController(composeSheet, animated: true, completion: nil)

    

像这样制作函数。它将解决您的问题。当您调用此函数时，它会为您创建单元格，因此它不会得到零单元格

【参考方案2】：

它现在正在以最小的变化工作。谢谢大家！

 func screenshotPulseCell(sender: UIButton) 

    //Create the UIImage
    UIGraphicsBeginImageContext(plCell.frame.size)
    self.plCell.contentView.layer.renderInContext((UIGraphicsGetCurrentContext())!)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    //Save it to the camera roll
    UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)

    //share the image to Social Media
    let composeSheet = SLComposeViewController(forServiceType: SLServiceTypeFacebook)
    composeSheet.setInitialText("My Pulse!")
    composeSheet.addImage(image)

    presentViewController(composeSheet, animated: true, completion: nil)