Detecting Left and Right scroll in UIScrollView with paging enabled.

gistfile1.txt

typedef enum {
	kScrollDirectionLeft = -1,
	kScrollDirectionNone,
	kScrollDirectionRight
}ScrollDirection;

-(void) scrollEffectInDirection:(ScrollDirection) direction{
	ContentView *previousPageView = (ContentView *)[self.pageScrollView viewWithTag:kPreviousPageTag];
	ContentView *currentPageView = (ContentView *)[self.pageScrollView viewWithTag:kCurrentPageTag];
	ContentView *nextPageView = (ContentView *)[self.pageScrollView viewWithTag:kNextPageTag];
	
	switch (direction) {
		case kScrollDirectionNone:
			[self fillPageView:currentPageView withPageNumber:self.currentPage.pageNumber];
			[self fillPageView:previousPageView withPageNumber:self.currentPage.pageNumber - 1];
			[self fillPageView:nextPageView withPageNumber:self.currentPage.pageNumber + 1];
			break;
			
		case kScrollDirectionRight:{
			// The previous page is free. Make it the next page.
			CGRect previousPageViewRect = nextPageView.frame;
			previousPageViewRect.origin.x += PAGE_WIDTH;
			previousPageView.frame = previousPageViewRect;
			
			// Fill the page.
			[self fillPageView:previousPageView withPageNumber:self.currentPage.pageNumber + 1];
			
			// Rearrange the page tag's.
			nextPageView.tag = currentPageView.tag;
			currentPageView.tag = previousPageView.tag;
			previousPageView.tag = kNextPageTag;
			
			// Update the page control.
			[pageControl gotoNextPage];
		}
			break;
			
		case kScrollDirectionLeft:{
			// The next page is free. Make it the previous page.
			CGRect nextPageViewRect = previousPageView.frame;
			nextPageViewRect.origin.x -= PAGE_WIDTH;
			nextPageView.frame = nextPageViewRect;
			
			// Fill the page.
			[self fillPageView:nextPageView withPageNumber:self.currentPage.pageNumber - 1];
			
			// Rearrange the page tag's.
			previousPageView.tag = currentPageView.tag;
			currentPageView.tag = nextPageView.tag;
			nextPageView.tag = kPreviousPageTag;
			
			// Update the page control.
			[pageControl gotoPreviousPage];
		}
			break;
			
		default:
			break;
	}
	[self inspectPageHighlightion];
}

-(void) scrollViewDidScroll:(UIScrollView *)scrollView {
	// Get the x of current page.
	int currentPageX = (self.currentPage.pageNumber - 1) * PAGE_WIDTH;
	
	if (self.pageScrollView.contentOffset.x >= currentPageX + PAGE_WIDTH) {
		// User scrolled to right.
		[self scrollEffectInDirection:kScrollDirectionRight];
	}else if (self.pageScrollView.contentOffset.x <= currentPageX - PAGE_WIDTH) {
		// User scrolled to left.
		[self scrollEffectInDirection:kScrollDirectionLeft];
	}
}