iOS6 UICollectionView and UIPageControl - How to get visible cell?

Question

While studying iOS6 new features I got a question about UICollectionView.
I am currently testing it with Flow layout and the scroll direction set to horizontal, scrolli

Answer 1

I would recommend a little tuned calculation and handling as it will update page control immediately in any scroll position with better accuracy.

The solution below works with any scroll view or it subclass (UITableView UICollectionView and others)

in viewDidLoad method write this

scrollView.delegate = self

then use code for your language:

Swift 3

func scrollViewDidScroll(_ scrollView: UIScrollView) 
    {
       let pageWidth = scrollView.frame.width
       pageControl.currentPage = Int((scrollView.contentOffset.x + pageWidth / 2) / pageWidth)
    }

Swift 2:

func scrollViewDidScroll(scrollView: UIScrollView) 
{
   let pageWidth = CGRectGetWidth(scrollView.frame)
   pageControl.currentPage = Int((scrollView.contentOffset.x + pageWidth / 2) / pageWidth)
}

Objective C

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat pageWidth = self.collectionView.frame.size.width;
    self.pageControl.currentPage = (self.collectionView.contentOffset.x + pageWidth / 2) / pageWidth;
}