Writing image metadata (EXIF/TIFF/IPTC) to image file in OS X

Question

I am creating a photo editing app, and so far I\'ve managed to read the metadata from image files successfully (after getting an answer to this question: Reading Camera data

Answer 1

Found an answer from another StackOverflow question: How do you overwrite image metadata?:

(code taken from that question itself and modified for my needs, which contains the answer to my question)

//assuming I've already loaded the image source and read the meta
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef) data, NULL);
CFStringRef imageType = CGImageSourceGetType(source);

//new empty data to write the final image data to
NSMutableData *resultData = [NSMutableData data];
CGImageDestinationRef imgDest = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)(resultData), imageType, 1, NULL);

//copy image data
CGImageDestinationAddImageFromSource(imgDest, source, 0, (__bridge CFDictionaryRef)(window.cachedMetadata));
BOOL success = CGImageDestinationFinalize(imgDest);

This worked perfectly for writing back all the metadata including EXIF, TIFF, and IPTC.

Answer 2

You could try either using, or looking at the code in, the "exiv2" tool maybe.