Create a c file, XCode would ask you whether to generat the bridging file. You just need to say yes.
Then you will have three files in this example.
factorial.h
factorial.c
{ProjectName}-Bridging-Header.h
factorial.h
#ifndef factorial_h
#define factorial_h
#include <stdio.h>
long factorial(int n);
#endif /* factorial_h */
factorial.c
#include "factorial.h"
long factorial(int n) {
if (n == 0 || n == 1) return 1;
return n * factorial(n-1);
}
{ProjectName}-Bridging-Header.h
#include "factorial.h"