Tengo el siguiente código que permitirá al usuario ingresar su nombre completo en un cuadro de alerta;

//Creates the alert box
            UIAlertController *alertController = [UIAlertController
                                                  alertControllerWithTitle:@"Congratulations"
                                                  message:@"You Have The High Score, Enter Your Name"
                                                  preferredStyle:UIAlertControllerStyleAlert];
            //Adds a text field to the alert box
            [alertController addTextFieldWithConfigurationHandler:^(UITextField *textField)
            {
              textField.placeholder = NSLocalizedString(@"Enter Full Name", @"Fullname");
            }];

            [self presentViewController:alertController animated:YES completion:nil];
            //Creates a button with actions to perform when clicked
            UIAlertAction *SaveAction = [UIAlertAction
                                         actionWithTitle:NSLocalizedString(@"SAVE",@"Save Action")
                                         style:UIAlertActionStyleDefault
                                         handler:^(UIAlertAction *action)
                                         {
                                             //Stores what has been inputted into the NSString Fullname
                                             NSString *Fullname = alertController.textFields.firstObject;
                                             NSLog(@"Name Stored %@",Fullname);


                                            [self performSegueWithIdentifier:@"NoNextSlide" sender:self];

                                         }];

            [alertController addAction:SaveAction];

Lo notarás en la línea;

NSLog(@"Name Stored %@",Fullname);

Esto devolverá lo siguiente;

2015-03-03 11:54:19.374 Master Game[1864:26681] Name Stored <_UIAlertControllerTextField: 0x7f9cf61ed780; frame = (4 4; 229 16); text = 'Shaun'; clipsToBounds = YES; opaque = NO; gestureRecognizers = <NSArray: 0x7f9cf6084bd0>; layer = <CALayer: 0x7f9cf61854b0>>

¿Cómo obtengo solo el 'Shaun' ingresado desde allí para poder guardarlo y usarlo en el futuro?