EXIF data read and write

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?

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}"].