YQScrollViewNested

scrollView嵌套列表滚动视图以达到平滑滚动的效果微博个人主页以及各大外卖平台都有类似效果

实现原理

最外层是个scrollView，headerView作为scrollView的子视图放在顶部，然后是分类工具栏topBar 和 pageView，重点关注解决外层scrollView和pageView中subScrollView手势冲突

最初尝试用scrollView的scrollEnabled属性控制外层和内部滚动视图滚动时机，在代理方法scrollViewDidScroll中进行判断，外层scrollView划出150后，停止响应滚动，这时手指再滑动，自然就是展示内容的subScrollView响应了。用户并不总是完美的在滑动了150 pt后，停下手。然后再开始进行下一次的滑动。如果用户一次性滚了160，外层ScrollView就会在滚动到150后停止响应，此时因为是一次手势，subScrollView也不会响应。用户就会有被中断的感觉，需要第二次滑动才能继续滚动

因此换了一种思路，首先在外层scrollView中通过手势的代理方法允许外层scrollView和内部ScrollView同时响应滚动手势,

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

然后用contentOffset控制滚动时机

#pragma mark - UIScrollViewDelegate

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat offsetY = scrollView.contentOffset.y;
    UIViewController *subVC = [self.pagerController.visibleControllers firstObject];
    UIScrollView *subScrollView = subVC.subScroller;
    if (subScrollView.contentOffset.y > 0 || offsetY > _kHeaderViewHeight) 
    {
        self.contentOffset = CGPointMake(0.0, _kHeaderViewHeight);
    }
}

#pragma mark - YQSubControllerDelegate

- (void)subScrollViewDidScroll:(UIScrollView *)scrollView
    {
    if (self.contentOffset.y < _kHeaderViewHeight)
    {
        scrollView.contentOffset = CGPointZero;
        scrollView.showsVerticalScrollIndicator = false;
    }else
    {
        scrollView.showsVerticalScrollIndicator = YES;
    }
}

YQScrollView 1.0.0

YQScrollView 1.0.0

YQScrollView 1.0.0

YQScrollViewNested