ios - DidSelectItemAt Collection View 问题

Question

我在 UICollectionViewCell 中使用 didSelectItemAt 时遇到问题。我正在使用第三方框架从库中选择多张照片。然后，所选 Assets 将被传输并存储在 PHAssets 数组中。我使用一个小脚本在点击图像时自定义预览图像。 (它基本上将图像扩展到全屏并放入，然后您可以向上或向下滑动以将其关闭)。问题不在于图像，它们正确显示在我的自定义 UICollectionViewCell 中。问题是当我点击它们时。由于某种原因，它给出了错误的图像，我不确定为什么。

var cameraPhotoUIImage: UIImage?
var assets = [PHAsset]()
lazy var assetsTurnedIntoImages =
{
    return  [UIImage]()
}()

lazy var imageManager = {
    return PHCachingImageManager()
}()

extension PhotoVC : UICollectionViewDataSource, UICollectionViewDelegate
{
    func setupCollectionView()
    {
        collectionView.dataSource = self
        collectionView.delegate = self
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
    {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "PhotoPostCVCell", for: indexPath) as! PhotoPostCVCell
        if let takenImage = cameraPhotoUIImage
        {
            cell.cellImage.image = takenImage
        }
        if assets.count > 0
        {
            let asset = assets[indexPath.row]
            imageManager.requestImage(for: asset, targetSize: PHImageManagerMaximumSize, contentMode: .aspectFill, options: nil)
            { (image, info) in
                cell.cellImage.contentMode = .scaleAspectFill
                cell.cellImage.image = image!
                self.assetsTurnedIntoImages.append(image!)
            }
        }
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
    {
        if assets.count > 0
        {
            return assets.count
        }
        else
        {
            return 1
        }
    }

    // MARK: Preview Selected Image
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        let postStoryboard = UIStoryboard(name: Storyboard_Post, bundle:nil)

        if let destinationVC = postStoryboard.instantiateViewController(withIdentifier: "PreviewImageVC") as? PreviewImageVC
        {
            destinationVC.allowedDismissDirection = .both
            destinationVC.maskType = .clear
            if cameraPhotoUIImage != nil
            {
                destinationVC.transferedImageToPreview.image = cameraPhotoUIImage
                destinationVC.showInteractive()
            }
            if assetsTurnedIntoImages.count > 0
            {
                print("Selected image to preview:",assetsTurnedIntoImages[indexPath.row]  )
                destinationVC.transferedImageToPreview.image = assetsTurnedIntoImages[indexPath.item]
                destinationVC.showInteractive()
            }

        }
    }
}

Answer 1

您应该更新 requestImage 方法。 requestImage 方法看起来像异步的。因此该请求不会等待 block 完成。如果你像这样更新你的 block ，它应该可以工作。

    imageManager.requestImage(for: asset, targetSize: PHImageManagerMaximumSize, contentMode: .aspectFill, options: nil)
            { (image, info) in
               DispatchQueue.main.async {
               let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "PhotoPostCVCell", for: indexPath) as! PhotoPostCVCell
               cell.cellImage.contentMode = .scaleAspectFill
               cell.cellImage.image = image!
               self.assetsTurnedIntoImages.append(image!)
               }
    }