如果再次单击标签栏项目，请滚动到UIView的顶部

Question

我有一个自定义标签栏，添加了基于索引标记选择的UIView的子视图。

- (IBAction)onTabSelectionChange:(id)sender {
    UIButton *btn = (UIButton*)sender;

    previousIndex = currentIndex;
    currentIndex = btn.tag;

    if (btn.tag == previousIndex){
       // scroll to top of previousIndex view
    } else {
        if (previousIndex != 0){
            UIButton *btnpreviousIndex = (UIButton*)[tabView viewWithTag:previousIndex];

            if (btnpreviousIndex != nil && previousIndex != -1){
                [btnpreviousIndex setSelected:NO];
            }  
            [btn setSelected:YES];
        }
    }
    appDelegate.currentTab = currentIndex;

    switch (currentIndex) {
        case TABHOME: {
            UINavigationController *navController = [appDelegate.arrViewControllers objectAtIndex:0];
            navController.navigationBarHidden = YES;
            [navController popToRootViewControllerAnimated:NO];
            [self presentThisView: navController];
        }
            break;
        case TABTIMELINE: {
            UINavigationController *navController = [appDelegate.arrViewControllers objectAtIndex:1];
            [self presentThisView: navController];
        }
            break;
        case TABNOTIFICATION: {
            self.badgeLabel.hidden = YES;
            UINavigationController *navController = [appDelegate.arrViewControllers objectAtIndex:2];
            [self presentThisView: navController];
            break;
        }
        case TABMISCELLANEOUS: {
            UINavigationController *navController = [appDelegate.arrViewControllers objectAtIndex:3];
            [self presentThisView: navController];
            break;
        }
        default:
            break;
    }
}

如何检索当前视图以将其滚动到顶部？

任何帮助将不胜感激。谢谢！