判断滑动方向UITableView

CGFloat lastContentOffset;  //ScoreView 滑动位置


-(void)scrollViewWillBeginDragging:(UIScrollView*)scrollView{
     lastContentOffset = scrollView.contentOffset.y;
}


-( void )scrollViewDidScroll:( UIScrollView *)scrollView {
   if (scrollView. contentOffset.y < lastContentOffset )
   {
       //向上，隐藏导航栏
      [ self.navigationController setNavigationBarHidden : NO animated : YES ];
    } 
     else if (scrollView. contentOffset.y > lastContentOffset )
    {
       //向下
       [ self.navigationController setNavigationBarHidden : YES animated : YES ];
     }

}