print UUID to stdout

uuid.m

// xcrun gcc -framework Foundation -o uuid uuid.m
#import <Foundation/Foundation.h>
#include <stdio.h>

int main(int argc, char **argv) {
   CFUUIDRef uuid = CFUUIDCreate(NULL);
   CFStringRef str = CFUUIDCreateString(NULL, uuid);
   CFRelease(uuid);
   
   printf("%s\n", [(NSString*)str UTF8String]);
   CFRelease(str);

   return 0;
}