Geotagging JPEG with Core Foundation

I was searching a way to edit or add GPS metadata of JPEG files without using an external library inside a Mac Application. After looking on internet and reading the ImageIOKit documentation, I found an interesting post on the Apple Mailing List talking about this topic and an old bug related to it. It includes a code sample that is apparently working now (Mac Os X 10.8).  I just wanted to add some details about it :

• The values corresponding to the kCGImagePropertyGPSLatitudeRef/kCGImagePropertyGPSLongitudedRef keys are expected to be of type NSString.
• The values corresponding to the kCGImagePropertyGPSLatitude/kCGImagePropertyGPSLongitude keys are expected to be of type NSNumber.

	CGImageSourceRef originalImageSource = CGImageSourceCreateWithURL((CFURLRef)imageURL, NULL);
	//get gps metadata
	NSDictionary *metadata = (NSDictionary *)CGImageSourceCopyPropertiesAtIndex(originalImageSource,0,NULL);
	//make the metadata dictionary mutable so we can add properties to it
	NSMutableDictionary *metadataAsMutable = [[metadata mutableCopy]autorelease];
	[metadata release];
	//get mutable gps data
	NSMutableDictionary *GPSDictionary = [[[metadataAsMutable objectForKey:(NSString *)kCGImagePropertyGPSDictionary]mutableCopy]autorelease];
	if(!GPSDictionary)
	{
	GPSDictionary = [NSMutableDictionary dictionary];
	}
	//Upate latitude longitude
	// latRef and lonRef are NSString
	[GPSDictionary setObject:[NSNumber numberWithFloat:lat] forKey:(NSString*)kCGImagePropertyGPSLatitude];
	[GPSDictionary setObject:latRef forKey:(NSString*)kCGImagePropertyGPSLatitudeRef];
	[GPSDictionary setObject:[NSNumber numberWithFloat:lon] forKey:(NSString*)kCGImagePropertyGPSLongitude];
	[GPSDictionary setObject:lonRef forKey:(NSString*)kCGImagePropertyGPSLongitudeRef];
	//add our modified GPS data back into the image's metadata
	[metadataAsMutable setObject:GPSDictionary forKey:(NSString *)kCGImagePropertyGPSDictionary];
	NSLog(@"Updated metadata: %@", metadataAsMutable);
	// Create a new image source that reads the TIFF data that we get from our NSImage.
	NSData *imageData = [newImage TIFFRepresentation];
	CGImageSourceRef finalImageSource = CGImageSourceCreateWithData((CFDataRef)imageData, NULL);
	// Create an image destination. This will take the image data from our source, and write it along with the metadata we read above
	// into a file in the correct format.
	CGImageDestinationRef imageDestination = CGImageDestinationCreateWithURL((CFURLRef)imageURL, imageType, 1, NULL);
	CGImageDestinationAddImageFromSource(imageDestination, finalImageSource, 0, (CFDictionaryRef)metadataAsMutable);
	if (!CGImageDestinationFinalize(imageDestination))
	{
	// The sample code doesn't do any specific error handling in this case. This would be an appropriate
	// place to notify the user, put up an alert, etc.
	}

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