宝宝详情页效果

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
  
    float diff = scrollView.contentOffset.y;
    
    // 向上滑
    if (diff >= 0) {
        self.loopView.y = diff * 0.5;
    } else {
        self.loopView.y = diff;
        self.contentView.y = KLoopViewH - 0.5 * diff;
    }
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {

    CGFloat alpha = (scrollView.contentOffset.y + KLoopViewH) / (KLoopViewH - KNavigationBarH);
    if (alpha >= 1) alpha = 1;
    self.navView.alpha = alpha;
}