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

Answer 1

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)
            }
        }
    }