下滑隱藏導航欄 上滑出現
-(void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
{
if(velocity.y>0)
{
self.navigationController.navigationBar.hidden = YES;
}
else
{
self.navigationController.navigationBar.hidden = NO;
}
}
