#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        NSArray *args = [[NSProcessInfo processInfo] arguments];

        if ([args count] < ) {

            printf("USAGE:\n\tuti <filenameExtension>\nEXAMPLE:\n\tuti jpg png\n");

            exit(EXIT_SUCCESS);

        }

        NSArray *extensions = [args subarrayWithRange:NSMakeRange(, [args count] - )];

        for (NSString *filenameExtension in extensions) {

            NSString *UTI = (__bridge_transfer NSString *)UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)filenameExtension, NULL);

            NSString *contentType = (__bridge_transfer NSString *)UTTypeCopyPreferredTagWithClass((__bridge CFStringRef)UTI, kUTTagClassMIMEType);

            printf("%s\nUTI: %s\nContentType: %s\n",[filenameExtension UTF8String] , [UTI UTF8String], [contentType UTF8String]);

        }

    }

    return ;

}

$ uti jpg png

jpg

UTI: public.jpeg

ContentType: image/jpeg

png

UTI: public.png

ContentType: image/png