UIRefreshControl for “Pull Up” to refresh?

Question

How do I add UIRefreshControl to bottom of a UIColloectionView? That means how does it work when It comes to Scroll up (to see old data or something)?

Answer 1

You can't. You can't really customise UIRefreshControl at all.

Answer 2

Here is a CCBottomRefreshControl category for UIScrollView class (parent of UICollectionView class) that implements bottomRefreshControl property. It's compatible with both iOS 6 and 7 native refresh controls.

Answer 3

You can't use UIRefreshControl to do that, but if you're ok with a simpler solution, you could just set up your collection view to automatically load more data when you scroll to the bottom. (Incidentally, this is a far more common user interface ... the pull up to refresh is not common, but automatically retrieving more data when you hit the bottom is.)

The most primitive rendition of that would be to respond to the UIScrollViewDelegate method and determine if you've scrolled to the bottom of the collection view (which is, itself, a subclass of the UIScrollView):

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    if ((scrollView.contentOffset.y + scrollView.frame.size.height) >= scrollView.contentSize.height)
    {
        if (!self.isLoadingMoreData)
        {
            self.loadingMoreData = YES;

            // proceed with the loading of more data
        }
    }
}

Even better, if you have more data to load, show a cell at the bottom, that says "please wait, loading more data", perhaps with a UIActivityIndicatorView. For example, if you have more data to load, add a section to the end with this one cell. If you format this additional cell properly (e.g. a single cell that goes all the way across the collection view), it could definitely render the effect you're looking for.