Soy nuevo en el desarrollo de Objective-C, y estoy tratando de filtrar el contenido de un UITableView agrupado.

Esto es lo que hice pero todavía no funciona:

- (void)filterContentForSearchText:(NSString *)searchText scope:(NSString *)scope
{
     NSPredicate *resultPredicate = [NSPredicate predicateWithFormat:@"SELF CONTAINS[cd] %@", searchText];;


    //activities is table that contains my objects that I display their contents in the table
    self.filteredData = [activities filteredArrayUsingPredicate:resultPredicate];
}

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller
shouldReloadTableForSearchScope:(NSInteger)searchOption
{
    [self filterContentForSearchText:[self.searchDisplayController.searchBar text] scope:
     [[self.searchDisplayController.searchBar scopeButtonTitles]
      objectAtIndex:searchOption]];

    // Return YES to cause the search result table view to be reloaded.
    return YES;
}
//activite is my object that I use to desplay its attribut in table
IPADActivity *activite ;
    if (ThetableView == self.searchDisplayController.searchResultsTableView) {
        activite = [self.filteredData objectAtIndex:indexPath.row];


    } 
    else{
        activite = [[objects
                      objectForKey:[objectsIndex objectAtIndex:indexPath.section]] objectAtIndex:indexPath.row];
    }

Cualquier sugerencia por favor