Creating an onscroll ajax loader for iPhone (web app)

I was wondering if it's possible to create an effect of auto loader while scrolling on iPhone, something like this

If it's not possible, than how would you go about to program something similar to facebook's page refresher (when you scroll up/down) and it retrieves in开发者_如何学Pythonfo.

Any help would be greatly appreciated on the matter, Thanks.

See if this example helps LazyTableImages.

Or you can try to implement it in following way-

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    //Find what needs to be downloaded and download it.
}