I need to save an image in Data/NSData format on a particular album on iOS device. New data structure is important because the raw image data is generated with an algorithm. I've tried different ways to store this raw data, but every used method, apply some data correction on the data to make the image "conform" to the (JPEG/HEIC/PNG) specifications, and I don't want this.  Let's make an example: I edit the data on the image, adding on the tail (or in the middle, the behavior is the same) new values, 0xAA 0xBB, 0xCC. I want to save the image with this value at the end of the image bytes. Original IMAGE -VS- CUSTOM IMAGE 35 1E 49 35 1E 49 A4 A8 B0 A4 A8 B0 1F FF D9 1F FF D9 ••••••••••••••••••••AA BB CC The only way to save the image AS-IS is to write a file using writeToFile, like this: Data().write(to: URL(string: "/path/image.png")) In this way the data content is preserved and all is fine BUT if I need to save this image to a particular album or to camera roll the image will be edited by iOS, removing my final bytes that I've inserted (0xAA, 0xBB and 0xCC).  This because the iOS recalculate the CRC of the image? Code I've used PHAssetCreationRequest (from Photos framework):  PHPhotoLibrary.shared().performChanges({ PHAssetChangeRequest.creationRequestForAsset(from: image) }) { status, error in } used also UIImageWriteToSavedPhotosAlbum:  UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil). I've used also PHAdjustmentData value and passing my custom bytes,  asset.requestContentEditingInput(with: options, completionHandler: { input, info in let adjustmentData = PHAdjustmentData( formatIdentifier: self.formatIdentifier, formatVersion: self.formatVersion, data: myCustomData) let output = PHContentEditingOutput(contentEditingInput: input) output.adjustmentData = adjustmentData PHPhotoLibrary.shared().performChanges({ let request = PHAssetChangeRequest(for: asset) request.contentEditingOutput = output }, completionHandler: { success, error in if !success { print("can't edit asset: \(error)") } }) }) but in this case I receive a generic error without any explanation: can't edit asset: Optional(Error Domain=PHPhotosErrorDomain Code=-1 "(null)")  The problem is that when I load the image using PHAsset or whatever from the camera roll, the image doesn't contain my custom 0xAABBCC bytes at the end. Question: How can I preserve the raw byte information while saving an image to photo album?