Exifを付与し、/tmpに画像を保存するサンプルコード

setExifInfo.m

- (void)setExifInfo:(UIImage *)image {
    CGImageSourceRef cgImage = CGImageSourceCreateWithData((__bridge CFDataRef) UIImageJPEGRepresentation(image, 1), NULL);

    NSMutableDictionary *exifDict = [[NSMutableDictionary alloc] init];
    NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];
    [outputFormatter setDateFormat:@"yyyy:MM:dd HH:mm:ss"];
    NSString *original = [outputFormatter stringFromDate:[NSDate date]];
    [exifDict setObject:original forKey:(__bridge NSString *) kCGImagePropertyExifDateTimeOriginal];
    [exifDict setObject:original forKey:(__bridge NSString *) kCGImagePropertyExifDateTimeDigitized];

    NSMutableData *imageData = [[NSMutableData alloc] init];
    CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef) imageData, CGImageSourceGetType(cgImage), 1, nil);
    CGImageDestinationAddImageFromSource(destination, cgImage, 0, (__bridge CFDictionaryRef) [NSDictionary dictionaryWithObjectsAndKeys:
            exifDict, (__bridge NSString *) kCGImagePropertyExifDictionary, nil]);
    CGImageDestinationFinalize(destination);
    NSString *exportPath = [NSString stringWithFormat:@"%@%@", NSTemporaryDirectory(), @"exportWithExif.jpg"];
    [imageData writeToFile:exportPath atomically:YES];

    CFRelease(cgImage);
    CFRelease(destination);
}