How to get a UITableView's visible sections?

Question

UITableView provides the methods indexPathsForVisibleRows and visibleCells, but how can I get the visible sections?

Answer 1

another solution, use 1 bit in your section header view's tag, like that

#define _TBL_TAG_SECTION(_TAG) ((_TAG)|(1<<30))
#define _TBL_TAG_CLEAR(_TAG) ((_TAG)&((1<<30)-1))
#define _TBL_TAG_IS_SECTION(_TAG) ((_TAG)>>30)

- (UIView*)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
    // alloc header view
    UIView *header = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1, 1)];
    header.tag = _TBL_TAG_SECTION(section);
    return header;
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGRect r = CGRectMake(scrollView.contentOffset.x, scrollView.contentOffset.y,
                      CGRectGetWidth(scrollView.frame),
                      CGRectGetHeight(scrollView.frame));
    for (UIView *v in [_tableView subviews]) {
        if ( CGRectIntersectsRect(r, v.frame) ) {
            if ( _TBL_TAG_IS_SECTION(v.tag) ) {
                NSLog(@"visible section tag %d", _TBL_TAG_CLEAR(v.tag));
            }
        }
    }
}