Compiling object c (.m) file to an object file(.o) in osx - objective-c

Question

Thanks for reviewing the problem. There is an object c file called try.m, and I complie it to an object file try.o with the command:
gcc -c try.m -o try.o -framework Foundation
the try.h is
int print_word( void );
The try.m is:
#include "try.h"
#import <Foundation/Foundation.h>
int print_word( void )
{
NSLog (#"say hello");
return 0;
}
Additionly, there is a main.c file, which contain the main() function, and it looks:
#include <stdio.h>
#include "try.h"
int main()
{
printf( "This is main\n");
}
I compile main.c to main.o by the following command:
gcc -o main.o -c main.c
Then, I link the main.o and try.o to form the executable file main:
gcc -o main main.o try.o
After these steps, the following errors happened:
enter image description here
The errors are:
Undefined symbols for architecture x86_64:
"_NSLog", referenced from:
_print_word in try.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
How could these errors be solved?

Answer 1

You need to link against the Foundation framework. You can do it all in a single command: gcc main.c try.m -framework Foundation.