tableview 的格式为UITableViewStylePlain，去掉headerview的黏连性

在viewcontroller中实现如下方法- (void)scrollViewDidScroll:(UIScrollView *)scrollView {        if (scrollView == _table) {        CGFloat sectionHeaderHeight = 50;        if (scrollView.contentOffset.y<=sectionHeaderHeight&&scrollView.contentOffset.y>=0) {            scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y, 0, 0, 0);        } else if (scrollView.contentOffset.y>=sectionHeaderHeight) {            scrollView.contentInset = UIEdgeInsetsMake(-sectionHeaderHeight, 0, 0, 0);        }    }   }

如果是ios7版本以上在viewdidload 实现以下代码，否则会出现滑动后区头被导航条遮住

   if ([[[UIDevice currentDevice]systemVersion]floatValue]>=7.0) {        self.edgesForExtendedLayout = UIRectEdgeNone;    }