accessing UIImage properties without loading in memory the image

Question

As you know the iphone guidelines discourage loading uiimages that are greater than 1024x1024.

The size of the images that i would have to load varies, and i would l

Answer 1

In Swift 5, with ImageIO,

extension URL{
    var sizeOfImage: CGSize?{
        guard let imageSource = CGImageSourceCreateWithURL(self as CFURL, nil)
            , let imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil) as? [AnyHashable: Any]
            , let pixelWidth = imageProperties[kCGImagePropertyPixelWidth as String] as! CFNumber?
            , let pixelHeight = imageProperties[kCGImagePropertyPixelHeight as String] as! CFNumber?
            else {
                return nil
        }
        var width: CGFloat = 0, height: CGFloat = 0
        CFNumberGetValue(pixelWidth, .cgFloatType, &width)
        CFNumberGetValue(pixelHeight, .cgFloatType, &height)
       }
       return CGSize(width: width, height: height)
    }
}

---

imageProperties[kCGImagePropertyOrientation as String] may be nil.

It is nil, I tested with png image file

as Apple says

kCGImagePropertyOrientation

The numeric value for this key encodes the intended display orientation for the image according to the TIFF and Exif specifications.