iOS: How to retrieve image dimensions without loading CGImage into memory

Updated

Mar 10, 2021 1:59 AM

Created

Mar 9, 2021 6:39 PM

Accessing Image Properties Without Loading the Image Into Memory

Sometimes you might want to retrieve certain properties from an image file, such as the image's dimensions or other metadata, without actually displaying the full-size image on screen. The simplest way to do that on iOS is using the class: The problem with this approach is that the entire image gets loaded into memory.

oleb.net

My version

func size(of imageSource: CGImageSource) -> CGSize? {
  let propertiesOptions = [kCGImageSourceShouldCache: false] as CFDictionary
  guard let properties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, propertiesOptions) as? [CFString: Any] else {
    return nil
  }
  
  guard
    let width = properties[kCGImagePropertyPixelWidth] as? CGFloat,
    let height = properties[kCGImagePropertyPixelHeight] as? CGFloat
  else {
    return nil
  }
  return CGSize(width: width, height: height)
}