Updated UIPageControl for paged UIScrollView

gistfile1.m

/**
 * Set the UIScrollView's delegate to self, and set self's protocol to UIScrollViewDelegate.
 *
 * This works with a horizontally paged scroll view but can be easily converted to vertical,
 * just switch all "width" to "height". 
 */
- (void)scrollViewDidScroll:(UIScrollView *)sender {
    // Switch the indicator when more than 50% of the previous/next page is visible
    CGFloat pageWidth = _scrollView.frame.size.width;
    int currentPage = ceil((_scrollView.contentOffset.x - pageWidth / 2) / pageWidth);
    _pageControl.currentPage = currentPage;
}