#import <objc/objc.h>
#import <objc/Object.h>
 
 
@interface TestObj : Object
{
    int num;
}
- (int)foo : (int)k;
@end
 
@implementation TestObj
 
- (int)foo: (int)k 
{
num =k;
    return 2+num;
}
 
int main()
{
    id obj = [[TestObj alloc] init];
   int y= [obj foo];
    printf ("\i \n",y);
    return 0;
}