title: Get frame of an UIBarButtonItem
body: <p>I have created an UIBarButtonItem inside a NavigationBar:</p>
  
  <pre><code>UIBarButtonItem *filtroFecha = [[[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemSearch target:self action:@selector(filtrarFecha:)]autorelease];
  
  
      self.navigationItem.rightBarButtonItems = [NSArray arrayWithObjects: addActivity, filtroFecha, nil];
  </code></pre>
  
  <p>Now I want to open a popover from this button, but I am not able to get the frame of the UIBarButtonItem.</p>
  
  <pre><code>if (_filtroActividadesView == nil) {
          self.filtroActividadesView = [[CRMFiltroActividadViewController alloc] init];
          _filtroActividadesView.delegate = self;
          self.filtroPopover = [[UIPopoverController alloc] 
                                    initWithContentViewController:_filtroActividadesView];               
      }
  
      [self.filtroPopover presentPopoverFromRect:CGRectMake(0, 0, 1400, 44) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionUp animated:YES];
  </code></pre>
  
  <p>Thanks!!</p>