EXIF data read and write

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?

There is already a `swift` tag. What is the point of including that in the question title? — Léo Natan, Oct 21 '16 at 14:04
Ok, I wanted to indicate that language matters. I will not use it in future. — Peter Silie, Oct 21 '16 at 15:40
Sure, I take what I can get. :-) I will see how far I get with it. — Peter Silie, Oct 21 '16 at 18:35

score 37 · Accepted Answer · edited Mar 17 '17 at 15:26

37

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}"].

edited Mar 17 '17 at 15:26

Leo Dabus

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answered Oct 21 '16 at 14:03

Eric Aya

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1

How could I write the EXIF data back to the image? – Genfood Jan 16 '18 at 15:05
this answer didn't mention "write", anyone knows it? – Amos Sep 13 '18 at 08:51
1

@Amos See https://stackoverflow.com/q/37992611/2227743 and https://stackoverflow.com/q/43920643/2227743 it looks like you can use these Q&A to find out how to write the exif. – Eric Aya Sep 13 '18 at 09:15
You can also user _kCGImagePropertyExifDictionary_ as key. – Areal-17 Aug 05 '19 at 14:43

Abhijeet Rai · Answer 2 · 2020-04-29T10:28:18.620

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
    }
}

For Swift 5+ you want to change the `data.withUnsafeBytes { (bytes: UnsafePointer)->Void in ...` to `data.withUnsafeBytes { let bytes = $0.baseAddress?.assumingMemoryBound(to: UInt8.self) ... }` — Teo Sartori, Dec 12 '19 at 10:52

score 1 · Answer 3 · answered Jun 22 '21 at 17:06

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
}

EXIF data read and write

3 Answers3

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