来自本地画廊的tableView中的照片使用了过多的RAM

Question

When I try to get photos using a URL from a local gallery I add them to a tableView using ALAssetsLibrary()

My code:

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

    var cell: AllPhotosTableViewCell!
    cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! AllPhotosTableViewCell

    let url = array[indexPath.section]["photos"] as! [AnyObject]

    if let image = cachedImages[url[indexPath.row] as! String] {        
        cell.imageViewImg.image = imageResize(image, sizeChange: CGSize(width: 50, height: 50))
    } else {

        let nsURL = NSURL(string: url[indexPath.row] as! String)!
        var loadError: NSError?

        asset.assetForURL(nsURL, resultBlock: { (asset) -> Void in

            if let ast = asset {
                let image = UIImage(CGImage: ast.defaultRepresentation().fullResolutionImage().takeUnretainedValue())
                self.cachedImages[url[indexPath.row] as! String] = image

                dispatch_async(dispatch_get_main_queue(), {

                    cell.imageViewImg.image = self.imageResize(image, sizeChange: CGSize(width: 50, height: 50))

                })
            }
        }, failureBlock: {(error) -> Void in
            loadError = error
        })
    }

    return cell
}

I try to minimize the size of photos, it helps a little but it doesn't solve the problem if I need to use many photos (10 or more...)

Answer 1

What is self.cachedImages . If that's a dictionary then your code is holding ALL of your images in memory, and as you scroll your memory footprint will grow and grow. The simplest way to fix that would be to get rid of the cache dictionary entirely and load the images from the asset library every time, but that might be slow.

If you are scaling your images to display them in a table view then load the asset, open a graphics context at the target size, render the image at your thumbnail size, and cache the thumbnail image.

You might also look at using NSCache , which acts like a dictionary but manages flushing objects when memory gets low.