躺坑了，self.navigationController.navigationBar setTranslucent:YES

使用https://github.com/coolbeet/CBStoreHouseRefreshControl中的CBStoreHouseRefreshControl做了一个组件，

死活执行不了，后来发现，修改导航图片了

if ([self.navigationController.navigationBar respondsToSelector:@selector(setBackgroundImage:forBarMetrics:)]) {
        [self.navigationController.navigationBar setBackgroundImage:image
                                                      forBarMetrics:UIBarMetricsDefault];
    }

#pragma mark - Notifying refresh control of scrolling
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    [self.storeHouseRefreshControl scrollViewDidScroll];
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    [self.storeHouseRefreshControl scrollViewDidEndDragging];
}

只有设置导航图片后，如果不设置

self.navigationController.navigationBar setTranslucent:YES

self.navigationController.navigationBar setTranslucent:NO

都不能触发这个消息，真吭爹啊