A simple pull-to-refresh for UIScrollViews. Whenever the UIScrollView ist pulled into a minus offset range auf at least -80, a reload method is triggered. But only if the scroll offset was in a range >= 0 before. This avoids infinite loading loops.

PullToRefresh.mm

- (void)scrollViewDidScroll:(UIScrollView *)sender
{
    if (sender.contentOffset.y >= 0)
    {
        self.inZero = YES;
    }
    
    // if the user pulled into abyss ...
    if (sender.contentOffset.y <= -80 && inZero == YES)
    {
        inZero = NO;
        
        // ... load content new
        [self reload];
    }
}