objective-C protocol concept

* ex)
// 1) you called presentModal method
[controlClassObject presentModalViewController:uiClassObject animated:YES];
// 2) If you want to close uiClassObject,  you use delegate mechanism like above .
//3) when cancel or ok event is occured in UIClass.  call delegate.Method1  and then
      controlmethod call '  [self dismissModalViewControllerAnimated:YES];