问题
I am currently trying to shoot photos within an app with the UIImagePickerController, saving it to the local database and upload them later to a service.
But it seems that the metadata (especially EXIF) are not bundled with this image automatically. I've tried to extract it like this:
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any])
{
self.imageDelegate?.saveImage( image: info[UIImagePickerControllerOriginalImage] as! UIImage, metadata: (info[UIImagePickerControllerMediaMetadata] as? NSDictionary)! )
// ...
}
Now I should have the image and the metadata, but how can I store it into a JPEG file? I need the GPS data in the image on the server.
I am currently creating the image directly from the UImage from the camera roll:
UIImageJPEGRepresentation(image,CGFloat(Constants.JPEG_QUALITY))
This will be stored and uploaded.
I've red that there might a possibility by using "CGImageDestination" but I have no idea how to use them in my case.
回答1:
My solution:
func toJpegWithExif(image: UIImage, metadata: NSDictionary, location: CLLocation?) -> Data? {
return autoreleasepool(invoking: { () -> Data in
let data = NSMutableData()
let options = metadata.mutableCopy() as! NSMutableDictionary
options[ kCGImageDestinationLossyCompressionQuality ] = CGFloat(Constants.JPEG_QUALITY)
// if location is available, add GPS data, thanks to https://gist.github.com/nitrag/343fe13f01bb0ef3692f2ae2dfe33e86
if ( nil != location ) {
let gpsData = NSMutableDictionary()
let altitudeRef = Int(location!.altitude < 0.0 ? 1 : 0)
let latitudeRef = location!.coordinate.latitude < 0.0 ? "S" : "N"
let longitudeRef = location!.coordinate.longitude < 0.0 ? "W" : "E"
// GPS metadata
gpsData[(kCGImagePropertyGPSLatitude as String)] = abs(location!.coordinate.latitude)
gpsData[(kCGImagePropertyGPSLongitude as String)] = abs(location!.coordinate.longitude)
gpsData[(kCGImagePropertyGPSLatitudeRef as String)] = latitudeRef
gpsData[(kCGImagePropertyGPSLongitudeRef as String)] = longitudeRef
gpsData[(kCGImagePropertyGPSAltitude as String)] = Int(abs(location!.altitude))
gpsData[(kCGImagePropertyGPSAltitudeRef as String)] = altitudeRef
gpsData[(kCGImagePropertyGPSTimeStamp as String)] = location!.timestamp.isoTime()
gpsData[(kCGImagePropertyGPSDateStamp as String)] = location!.timestamp.isoDate()
gpsData[(kCGImagePropertyGPSVersion as String)] = "2.2.0.0"
options[ kCGImagePropertyGPSDictionary as String ] = gpsData
}
let imageDestinationRef = CGImageDestinationCreateWithData(data as CFMutableData, kUTTypeJPEG, 1, nil)!
CGImageDestinationAddImage(imageDestinationRef, image.cgImage!, options)
CGImageDestinationFinalize(imageDestinationRef)
return data as Data
})
}
extension Date {
func isoDate() -> String {
let f = DateFormatter()
f.timeZone = TimeZone(abbreviation: "UTC")
f.dateFormat = "yyyy:MM:dd"
return f.string(from: self)
}
func isoTime() -> String {
let f = DateFormatter()
f.timeZone = TimeZone(abbreviation: "UTC")
f.dateFormat = "HH:mm:ss.SSSSSS"
return f.string(from: self)
}
}
The method converts the UIImage to a Jpeg with EXIF data from the camera plus an optional GPS location coming from CLLocationManager.
来源:https://stackoverflow.com/questions/52810822/saving-exif-data-to-jpeg-swift