gistfile1.txt

int main(int argc, char *argv[])
{
    //XYZPerson *person = [[XYZPerson alloc] init];
    XYZPerson *person = [XYZPerson person];
    if(person)
    {
        NSLog(@"Person is alive: %@", person);
        [person sayHello];
    }else{
        NSLog(@"No person, sorry!");
    }
    
    //XYZShoutingPerson *shoutingPerson = [XYZShoutingPerson person];
    
    return NSApplicationMain(argc, (const char **)argv);
}





//
//  XYZPerson.h

#import <Foundation/Foundation.h>

@interface XYZPerson : NSObject
+ (id)person;
- (void)sayHello;
- (void)saySomething:(NSString *)greeting;
@end



//
//  XYZPerson.m

#import "XYZPerson.h"

@implementation XYZPerson

+ (id)person
{
    return [[self alloc] init];
}

- (void)sayHello {
    [self saySomething:@"Hello World!"];
}

- (void)saySomething:(NSString *)greeting
{
    NSLog(@"%@", greeting);
}

@end