[self.tableView setContentOffset:CGPointMake(0,40)]

- (void)searchDisplayControllerWillEndSearch:(UISearchDisplayController *)controller

- (void)searchDisplayControllerWillEndSearch:(UISearchDisplayController *)controller

if ([NSThread isMainThread]) {
    NSLog(@"Yes it is the main thread.");
}

[self performSelectorOnMainThread:@selector(XXX) withObject:nil waitUntilDone:NO];

-(void)searchDisplayControllerDidEndSearch:(UISearchDisplayController *)controller{
    [self.tableView setContentOffset:CGPointMake(0,40)];
}