Using ReactiveCocoa to get rid of the scroll view delegate, to update a UIPageControl's currentPage as you scroll.

scrollviewcontroller.m

CGFloat pageWidth = CGRectGetWidth(self.scrollView.frame);

RAC(self.pageControl, currentPage) = [RACObserve(self.scrollView, contentOffset) map:^id(NSValue *value) {
    CGPoint contentOffset = [value CGPointValue];
    NSUInteger page = floor((contentOffset.x - pageWidth / 2) / pageWidth) + 1;
    
    return @(page);
}];