HelloTDDViewController.m

@implementation HelloTDDViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    GreetingFactory *greetingFactory = [[GreetingFactory alloc] init];
    _delegate = greetingFactory;
}

//...

- (IBAction)onButtonClick:(id)sender {
    NSString *name = _nameField.text;
    [_delegate sayHello:name toMyLittleFriend:self];
}

//...

@end