Need sample code to implement Paging Based UIScrollView - iphone

Question

I am new to iOS development. Can anyone give me a working sample project/ tutorial of paging based scrollview? I need to load more data in my table view from a webservice as user scrolls down.
I have spent a lot of time, but could not find anything that suits my need. Any help will be greatly appreciated.
I was able to figure out the solution of my problem. Now I am trying to detect scroll up and down based on the y offset difference. The problem is it always reads the drag to be downwards even if it is upward. This is how I am trying to detect the scroll direction:
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
CGPoint scrollOffSet = scrollView.contentOffset;
NSLog(#"Current Content offset: , y = %f", scrollOffSet.y);
NSLog(#"Previous offset , y = %f", self.previousYOffset);
if(scrollOffSet.y > self.previousYOffset)
{
self.previousYOffset = scrollOffSet.y;
NSLog(#"Scrolled Down");
self.nextPageNumber++;
//Here I send the request to fetch data for next page number
}
else {
NSLog(#"Scrolled up");
self.previousYOffset = scrollOffSet.y;
}
}
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
CGPoint scrollOffSet = scrollView.contentOffset;
NSLog(#"Current Content offset: y = %f", scrollOffSet.y);
}
The problem is: either i scroll up or down, it will always display "scrolled down", thus it goes to fetch data for next page number even if it was not intended to request. Plus, the y offset positions it returns on up/down scroll are also very confusing. Please guide me how to accurately detect an upside scroll?

Answer 1

Do you mean a "swipable" UIScrollView?
Paging a UIScrollView is quite easy. First make sure you have the pagingEnabled property set to YES. The UIScrollView will use it's own frame as the size of a page (like a viewport).
Use the contentSize property to determine the scrollable area.
Example:
//scrollView is a UIScrollView instance
int pageCount = 3;
scrollView.pagingEnabled = YES;
scrollView.contentSize = CGSizeMake(scrollView.frame.width*pageCount, scrollView.frame.height);