#iOS# 滑动背景图片跟着动

Horizontal

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat ratio = scrollView.contentOffset.x/scrollView.frame.size.width;
    _page = (int)floor(ratio);
    NSLog(@"%i",_page);
    if (ratio > -1 && ratio < 1) {
        [_glassScrollView1 scrollHorizontalRatio:-ratio];
    }
    if (ratio > 0 && ratio < 2) {
        [_glassScrollView2 scrollHorizontalRatio:-ratio + 1];
    }
}

Vertical

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    //translate into ratio to height
    CGFloat ratio = (scrollView.contentOffset.y + _foregroundScrollView.contentInset.top)/(_foregroundScrollView.frame.size.height - _foregroundScrollView.contentInset.top - _viewDistanceFromBottom);
    ratio = ratio<0?0:ratio;
    ratio = ratio>1?1:ratio;
    
    //set background scroll
    [_backgroundScrollView setContentOffset:CGPointMake(DEFAULT_MAX_BACKGROUND_MOVEMENT_HORIZONTAL, ratio * DEFAULT_MAX_BACKGROUND_MOVEMENT_VERTICAL)];
}