在ios 11中滚动collectionView时如何隐藏navigationBar？

Question

在iOS 11中，如果我们设置为隐藏，则在滚动tableView时会隐藏searchBar。滚动collectionView时如何隐藏searchBar，navigationBar和tabBar？向下滚动时取消隐藏所有内容？谢谢你的帮助...

Answer 1

1. UIViewController中的子类UIScrollViewDelegate（即class ViewController: UIViewController, UIScrollViewDelegate { codes... }）

2. 实现scrollViewDidScroll委托方法

   func scrollViewDidScroll(scrollView: UIScrollView) { 
       let pan = scrollView.panGestureRecognizer
       let velocity = pan.velocityInView(scrollView).y
       if velocity < -5 { 
           self.navigationController?.setNavigationBarHidden(true, animated: true) 
           self.navigationController?.setToolbarHidden(true, animated: true)
       } else if velocity > 5 {
           self.navigationController?.setNavigationBarHidden(false, animated: true)
           self.navigationController?.setToolbarHidden(false, animated: true)
       }
   }
   

Answer 2

将KTang接受的答案翻译成Objective-C：

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    UIPanGestureRecognizer *pan = scrollView.panGestureRecognizer;
    CGFloat velocity = [pan velocityInView:scrollView].y;

    if (velocity < -5) {
        [self.navigationController setNavigationBarHidden:YES animated:YES];
        [self.navigationController setToolbarHidden:YES animated:YES];
    } else if (velocity > 5) {
        [self.navigationController setNavigationBarHidden:YES animated:YES];
        [self.navigationController setToolbarHidden:YES animated:YES];
    }
}