foo.m

#import <Foundation/Foundation.h>

@interface ReferenceCounter : NSObject {
    id obj;
}
- (void)setObj:(id)_obj;
@end

@implementation ReferenceCounter
- (void)setObj:(id)_obj {
    obj = [_obj retain];
}
- (void)dealloc {
    [obj release];
    [super dealloc];
}
@end

int main() {
    id foo = [[NSObject alloc] init];
    NSLog(@"retainCount: %d", [foo retainCount]);

    id rctest = [[ReferenceCounter alloc] init];
    [rctest setObj:foo];
    NSLog(@"retainCount: %d", [foo retainCount]);

    [foo release];
    NSLog(@"retainCount: %d", [foo retainCount]);

    [rctest release];

    return 0;
}