EXIF data read and write - swift

Question

I searched for getting the EXIF data from picture files and write them back for Swift. But I only could find predefied libs for different languages.
I also found references to "CFDictionaryGetValue", but which keys do I need to get the data? And how can I write it back?

Answer 1

I'm using this to get EXIF infos from an image file:
import ImageIO
let fileURL = theURLToTheImageFile
if let imageSource = CGImageSourceCreateWithURL(fileURL as CFURL, nil) {
let imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil)
if let dict = imageProperties as? [String: Any] {
print(dict)
}
}
It gives you a dictionary containing various informations like the color profile - the EXIF info specifically is in dict["{Exif}"].

Answer 2

Swift 4
extension UIImage {
func getExifData() -> CFDictionary? {
var exifData: CFDictionary? = nil
if let data = self.jpegData(compressionQuality: 1.0) {
data.withUnsafeBytes {(bytes: UnsafePointer<UInt8>)->Void in
if let cfData = CFDataCreate(kCFAllocatorDefault, bytes, data.count) {
let source = CGImageSourceCreateWithData(cfData, nil)
exifData = CGImageSourceCopyPropertiesAtIndex(source!, 0, nil)
}
}
}
return exifData
}
}
Swift 5
extension UIImage {
func getExifData() -> CFDictionary? {
var exifData: CFDictionary? = nil
if let data = self.jpegData(compressionQuality: 1.0) {
data.withUnsafeBytes {
let bytes = $0.baseAddress?.assumingMemoryBound(to: UInt8.self)
if let cfData = CFDataCreate(kCFAllocatorDefault, bytes, data.count),
let source = CGImageSourceCreateWithData(cfData, nil) {
exifData = CGImageSourceCopyPropertiesAtIndex(source, 0, nil)
}
}
}
return exifData
}
}

Answer 3

You can use AVAssetExportSession to write metadata.
let asset = AVAsset(url: existingUrl)
let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetHighestQuality)
exportSession?.outputURL = newURL
exportSession?.metadata = [
// whatever [AVMetadataItem] you want to write
]
exportSession?.exportAsynchronously {
// respond to file writing completion
}