Swift how to modify exif info in images taken from mobile camera

Question

I use UIImagePickerController to pick images in my iOS App and I know exif info can be got by info[UIImagePickerControllerMediaMetadata]. But when I upload my image to my server by UIImage, most of exif info has been striped. I wonder whether I can add exif info to my image in Http request(image uploaded as jpg after that). If not, how should I solve this problem? I wanna change Make, Model attributes(in other words, what device was used to take this picture)

Below are my code snippets:

func Tapped() {
    let myPickerController = UIImagePickerController()

    myPickerController.delegate = self
    myPickerController.sourceType = UIImagePickerControllerSourceType.Camera
    myPickerController.allowsEditing = false
    self.presentViewController(myPickerController, animated: true, completion: nil)
}
func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {
    let image = info[UIImagePickerControllerOriginalImage] as? UIImage
    myImageView.image = image
    UIImageWriteToSavedPhotosAlbum(image!, self, #selector(ViewController.image(_:didFinishSavingWithError:contextInfo:)), nil)
    self.dismissViewControllerAnimated(true, completion: nil)
}

func myImageUploadRequest()
{

    let myUrl = NSURL(string: "http://XXXXXX/Uploadfile")

    let request = NSMutableURLRequest(URL:myUrl!)
    request.HTTPMethod = "POST"

    let param = [
        "userId"    : "7"
    ]

    let boundary = generateBoundaryString()

    request.setValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")


    let imageData = UIImageJPEGRepresentation(myImageView.image!, 1)

    if(imageData == nil)  { return; }

    request.HTTPBody = createBodyWithParameters(param, filePathKey: "file", imageDataKey: imageData!, boundary: boundary)



    myActivityIndicator.startAnimating()

    let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
        data, response, error in

        if error != nil {
            print("error=\(error)")
            return
        }

        // You can print out response object
        print("******* response = \(response)")

        // Print out response body
        let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
        print("****** response data = \(responseString!)")

        do{
            let json = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers) as? NSDictionary

        }catch{
            print(error)
        }


        dispatch_async(dispatch_get_main_queue(),{
            self.myActivityIndicator.stopAnimating()
            self.myImageView.image = nil
        })

    }

    task.resume()
}

func createBodyWithParameters(parameters: [String: String]?, filePathKey: String?, imageDataKey: NSData, boundary: String) -> NSData {
    let body = NSMutableData();

    if parameters != nil {
        for (key, value) in parameters! {
            body.appendString("--\(boundary)\r\n")
            body.appendString("Content-Disposition: form-data; name=\"\(key)\"\r\n\r\n")
            body.appendString("\(value)\r\n")
        }
    }

    let filename = "test.jpg"

    let mimetype = "image/jpg"

    body.appendString("--\(boundary)\r\n")
    body.appendString("Content-Disposition: form-data; name=\"\(filePathKey!)\"; filename=\"\(filename)\"\r\n")
    body.appendString("Content-Type: \(mimetype)\r\n\r\n")
    body.appendData(imageDataKey)
    body.appendString("\r\n")



    body.appendString("--\(boundary)--\r\n")

    return body
}

func generateBoundaryString() -> String {
    return "Boundary-\(NSUUID().UUIDString)"
}

extension NSMutableData {
    func appendString(string: String) {
        let data = string.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)
        appendData(data!)
    }
}

Pleo

Any updates on this? I too can't find a simple way of doing this. – Misconduct

Answer 1

Yes! Finally I made a trick to modify the EXIF info. At first, you can get EXIF info from info[UIImagePickerControllerMediaMetadata] and NSData without EXIF from picked UIImage by UIImageJPEGRepresentation. Then, you can create a new NSDictionary with modified EXIF info. After that, call my function in the following, you can get image NSData with modified EXIF!

func saveImageWithImageData(data: NSData, properties: NSDictionary, completion: (data: NSData, path: NSURL) -> Void) {

    let imageRef: CGImageSourceRef = CGImageSourceCreateWithData((data as CFDataRef), nil)!
    let uti: CFString = CGImageSourceGetType(imageRef)!
    let dataWithEXIF: NSMutableData = NSMutableData(data: data)
    let destination: CGImageDestinationRef = CGImageDestinationCreateWithData((dataWithEXIF as CFMutableDataRef), uti, 1, nil)!

    CGImageDestinationAddImageFromSource(destination, imageRef, 0, (properties as CFDictionaryRef))
    CGImageDestinationFinalize(destination)

    var paths: [AnyObject] = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let savePath: String = paths[0].stringByAppendingPathComponent("exif.jpg")

    let manager: NSFileManager = NSFileManager.defaultManager()
    manager.createFileAtPath(savePath, contents: dataWithEXIF, attributes: nil)

    completion(data: dataWithEXIF,path: NSURL(string: savePath)!)

    print("image with EXIF info converting to NSData: Done! Ready to upload! ")

}

Pleo

While printing, its all coming perfectly. But while retrieving the image after it is saved, the new metadata is not showing. Pls help! if let imageSource = CGImageSourceCreateWithData(imageData as CFData, nil) { let imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil) if let dict = imageProperties as? [String: Any] { print(dict) } } – Analemma

@DeviOS I have the same problem and I am trying to narrow it down now. I believe that the file itself is being saved without the EXIF itself it somehow gets lost somewhere – Hartzke

@ADProgress did you track it down why the metadata is not being retrieved after saving the image? – Corso

@MadhavThakker Yes. What it was at least in my code. When saving the file I was converting the data to jpegData and that created a brand new Data container without the EXIF information. But the data was already a jpegData so I only needed to save it rather than recreating it. – Hartzke

Answer 2

using and mergind some info from other posts, I approached problem using Dictionary in Swift. I used it in captureOutput of AVFounfation callback for AVCapturePhoto:

func photoOutput(_ output: AVCapturePhotoOutput,
                 didFinishProcessingPhoto photo: AVCapturePhoto,
                 error: Error?) {

    //retrieve exif information
    var photoFormatDescription: CMFormatDescription?
    CMVideoFormatDescriptionCreateForImageBuffer(kCFAllocatorDefault, photoPixelBuffer, &photoFormatDescription)

    var metadataAttachments: Dictionary = photo.metadata as Dictionary

    if var exifData = metadataAttachments["{Exif}"] as? [String: Any] {
        exifData[kCGImagePropertyExifUserComment as String] = "<whatever you want to write>"

    metadataAttachments[kCGImagePropertyExifDictionary as String] = exifData
    }

}

After that "metadataAttachments" is used to build final image (using CGImageDestinationAddImage in my case)

It seems to work (tried in a project build with Swift 4.0)

Hope it can help!

Wallie

How to use metadataAttachments to build final image? – Corso

Answer 3

Swift 5 Version of the accepted answer -

func saveImageWithImageData(data: NSData, properties: NSDictionary, completion: (_ data: NSData, _ path: NSURL) -> Void) {

    let imageRef: CGImageSource = CGImageSourceCreateWithData((data as CFData), nil)!
    let uti: CFString = CGImageSourceGetType(imageRef)!
    let dataWithEXIF: NSMutableData = NSMutableData(data: data as Data)
    let destination: CGImageDestination = CGImageDestinationCreateWithData((dataWithEXIF as CFMutableData), uti, 1, nil)!

    CGImageDestinationAddImageFromSource(destination, imageRef, 0, (properties as CFDictionary))
    CGImageDestinationFinalize(destination)

    let paths: [String] = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    let savePath: String = paths[0].appending("exif.jpg")

    let manager: FileManager = FileManager.default
    manager.createFile(atPath: savePath, contents: dataWithEXIF as Data, attributes: nil)

    completion(dataWithEXIF,NSURL(string: savePath)!)

    print("image with EXIF info converting to NSData: Done! Ready to upload! ")

}

Corso

This feature spoils the image quality. In my experience, the amount of data, unlike the original image, is reduced by two to three times. And visually, the image quality is much worse than after the CIContext().jpegRepresentation function. Do you know how to fix it? How can I control the quality of the resulting image? – Consumable

Answer 4

SWIFT 3

In case you're capturing a video and getting the CMSampleBuffer there is a way to update the EXIF metadata. In my case in iOS9 I didn't get the DateTimeOriginal, though in iOS10 the DataTimeOriginal was already in. Thus I had to put few additional key-values in.

self.stillCameraOutput.captureStillImageAsynchronously(from: connectionVideo) { (sampleBuffer, err) in
        if let err = err {
            blockCompletion(nil, err as NSError?)
        }
        else {
            if let sampleBuffer = sampleBuffer {
                let rawMetadata = CMCopyDictionaryOfAttachments(nil, sampleBuffer, CMAttachmentMode(kCMAttachmentMode_ShouldPropagate))
                let metadata = CFDictionaryCreateMutableCopy(nil, 0, rawMetadata) as NSMutableDictionary

                let exifData = metadata.value(forKey: "{Exif}") as? NSMutableDictionary

                print("EXIF DATA: \(exifData)")

                if let dateTime = exifData?["DateTimeOriginal"] as? String {
                    print("DateTime exists \(dateTime)")
                }
                else {
                    exifData?.setValue(Date().exifDate(), forKey: "DateTimeOriginal")
                }

                if let dateTime = exifData?["DateTimeDigitized"] as? String {
                    print("DateTime exists \(dateTime)")
                }
                else {
                    exifData?.setValue(Date().exifDate(), forKey: "DateTimeDigitized")
                }

                metadata.setValue(exifData, forKey: "{Exif}")

                CMSetAttachments(sampleBuffer, metadata as CFDictionary, CMAttachmentMode(kCMAttachmentMode_ShouldPropagate))

                let rawMetadata2 = CMCopyDictionaryOfAttachments(nil, sampleBuffer, CMAttachmentMode(kCMAttachmentMode_ShouldPropagate))
                let metadata2 = CFDictionaryCreateMutableCopy(nil, 0, rawMetadata2) as NSMutableDictionary

                let exifData2 = metadata2.value(forKey: "{Exif}") as? NSMutableDictionary

                print("EXIF DATA: \(exifData2)")

                if let dataImage = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(sampleBuffer) {
                    blockCompletion(dataImage, nil)
                }
                else {
                    blockCompletion(nil, nil)
                }
            }
            else {
                blockCompletion(nil, nil)
            }
        }
    }

Sabbat

I tried this method, but my rawMetadata is nil. Does this work on image data from AVCapturePhotoOutput? – Tyronetyrosinase

#43490123 can you ans this also – Anglice