UIActionSheetDelegate

En UIViewController, Tengo este código.

`@interface TapCounterViewController : UIViewController { IBOutlet UILabel *count; } -(IBAction)minus; -(IBAction)plus; -(IBAction)wannaZeroEng:(id)sender; -(IBAction)wannaZeroSpa:(id)sender; -(IBAction)linksSpa:(id)sender; -(IBAction)linksEng:(id)sender; -(IBAction)developerSpa:(id)sender; -(IBAction)developerEng:(id)sender; -(IBAction)vibrate:(id)sender;

@end`

Quiero que una ActionSheet ponga a Cero el contador. Y pusé este código.

-(IBAction)wannaZeroEng:(id)sender{
    UIActionSheet *actionSheet;
    actionSheet=[[UIActionSheet alloc] initWithTitle:@"Are you sure you want to reset the counter?"
        delegate:self
        cancelButtonTitle:@"No"
        destructiveButtonTitle:@"Yes. Reset."
        otherButtonTitles:nil];
    [actionSheet showInView:self.view];
    [actionSheet release];

}

-(void)actionSheet:(UIActionSheet *)actionSheet
clickedButtonAtIndex:(NSInteger)buttonIndex {
NSString *buttonTitle=[actionSheet buttonTitleAtIndex:buttonIndex];
if ([buttonTitle isEqualToString:@"Yes. Reset."]) {
        counter=counter - 1;
    count.text = [NSString stringWithFormat:@"%i",counter];
    }
}

Si en el delegate pongo self lo resetea bien, pero si pongo nil el contador no se resetea. Cuando asigno self, me dice que tengo que implementar el ActionSheetDelegate. La pregunta es como implemento el ActionSheetDelegate, y mantengo la IBOutlet que asigne al principio.