Open Radar

 
kCGImageDestinationLossyCompressionQuality has no effect when exporting PNG or TIFF to HEIF using CGImageDestination. JPG to HEIF works with compression option. HEIF to HEIF works with compression option.

func heifImageDataUsingDestination(at url: URL, compressionQuality : CGFloat) -> Data?  {
    
    guard let imageSource = CGImageSourceCreateWithURL(url as CFURL, nil) else { return nil }
    guard let cgImage = CGImageSourceCreateImageAtIndex(imageSource, 0, nil) else { return nil }
    var mutableData = NSMutableData()
    guard let imageDestination = CGImageDestinationCreateWithData(mutableData, "public.heic" as CFString, 1, nil) else { return nil }
    let options = [ kCGImageDestinationLossyCompressionQuality: compressionQuality ] as CFDictionary
    CGImageDestinationAddImage(imageDestination, cgImage, options)
    let success = CGImageDestinationFinalize(imageDestination)
    if success {
        return mutableData as Data
    }
    return nil
}


1. Get URL of any PNG image
2. Use CGImageDestination to export new HEIC image with kCGImageDestinationLossyCompressionQuality parameter of 0.01
3. Use CGImageDestination to export new HEIC image with kCGImageDestinationLossyCompressionQuality parameter of 0.9
4. Compare these images

Expected results:
Image from step 2 smaller than image from step 3

Current results:
Image from step 2 is the same as step 3

14.4 (23E214)
Version 15.3 (15E204a)