在 UITableView 上显示 UISearchController 向下滚动

Question

我的 UITableView 上面有一个 UISearchController，我的 table 有很多记录。当用户在 table 中转到底部时，他必须返回顶部才能看到搜索栏。下面你可以看到我是如何创建搜索栏的：

- (void) showSearchBar {
    _searchController = [[UISearchController alloc] initWithSearchResultsController:nil];

    self.searchController.searchResultsUpdater = self;
    self.searchController.searchBar.placeholder = nil;
    [self.searchController.searchBar sizeToFit];
    self.tableView.tableHeaderView = self.searchController.searchBar;
    //self.sharedNavigationItem.titleView = _searchController.searchBar;

    self.searchController.delegate = self;
    self.searchController.dimsBackgroundDuringPresentation = NO; // default is YES
    self.searchController.searchBar.delegate = self; // so we can monitor text changes + others
        self.definesPresentationContext = YES;
    _searchController.hidesNavigationBarDuringPresentation = NO;

}

我想知道如何在 table 中向下滚动（向上）时显示搜索栏，而在 table 中向上滚动（向下）时如何将其隐藏我在 table 的底部。

Answer 1

如果您使 header 保持在顶部，则搜索字段应该保持可见

UITableViewStylePlain: A plain table view. Any section headers or footers are displayed as inline separators and float when the table view is scrolled.

UITableViewStyleGrouped: A table view whose sections present distinct groups of rows. The section headers and footers do not float.

Answer 2

搜索栏可以任意放置在UI中。创建 table 视图的同级视图，例如放置在 table 上方。给那个视图一个最初设置为 44px 的高度约束，并为视图和约束提供出口...

@property(weak,nonatomic) IBOutlet UIView *searchBarContainerView;
@property(weak,nonatomic) IBOutlet NSLayoutConstraint *searchBarHeightConstraint;

现在，您的设置代码更改为：

// ...
self.searchBarHeightConstraint.constant = self.searchController.searchBar.bounds.size.height;
[self.searchBarContainerView addSubview:self.searchController.searchBar];
// ...

Answer 3

我正在尝试帮助您解决我所做的事情，希望对您有所帮助。这就是我在 table 视图的 header 视图中添加标签的方式，我试图用您的搜索控制器替换它；

-(UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
        CGRect frame = CGRectMake(0, 0, tableView.frame.size.width, 40);
        UIView *view = [[UIView alloc] initWithFrame:frame];
        view.backgroundColor = [UIColor clearColor];
        view.autoresizingMask = UIViewAutoresizingFlexibleWidth;
        _searchController = [[UISearchController alloc] initWithSearchResultsController:nil];
        self.searchController.searchResultsUpdater = self;
        self.searchController.searchBar.placeholder = nil;
        [self.searchController.searchBar sizeToFit];
        [view addSubview:_searchController];
        view.tag = 123;
        return view;
}

如果您希望在拖动移动完成时隐藏效果，请使用以下方法；

-(void)scrollViewWillEndDragging:(UIScrollView *)scrollView 
                    withVelocity:(CGPoint)velocity 
             targetContentOffset:(inout CGPoint *)targetContentOffset{
    if (velocity.y > 0){
    NSLog(@"up");
    [self.view viewWithTag:123].hidden = true;
}
if (velocity.y < 0){
    NSLog(@"down");
    [self.view viewWithTag:123].hidden = false;
}

要立即更改滚动 table 视图，请使用以下方法：

-(void)scrollViewDidScroll:(UIScrollView *)scrollView //working delegate
{
    if ([scrollView.panGestureRecognizer translationInView:scrollView].y > 0) {
        NSLog(@"down");
        [self.view viewWithTag:123].hidden = false;
    } else {
        NSLog(@"up");
        [self.view viewWithTag:123].hidden = true;
    }
}

Answer 4

经过一番搜索，我想到了一些新的答案，希望对您有所帮助！

确定滚动方向：

BOOL showSearch;

-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if ([scrollView.panGestureRecognizer translationInView:scrollView].y > 0) {
        // down
        showSearch = true;
    } else {
        // up
        showSearch = false;
    }
}

-(void)scrollViewWillEndDragging:(UIScrollView *)scrollView
                    withVelocity:(CGPoint)velocity
             targetContentOffset:(inout CGPoint *)targetContentOffset{
     if (showSearch) {
         [self addSearch];
     }
     else {
         [self removeSearch];
     }
     [_tableView reloadData];
}

添加和删除 SearchController：

-(void)addSearch {    
     if (!_searchController){

     _searchController = [[UISearchController alloc] initWithSearchResultsController:nil];

    _searchController.searchResultsUpdater = self;
    [_searchController.searchBar sizeToFit];
    _tableView.tableHeaderView = _searchController.searchBar;

    _searchController.delegate = self;
    _searchController.dimsBackgroundDuringPresentation = NO;

    self.definesPresentationContext = YES;
    _searchController.active = NO;

    _searchController.searchResultsUpdater = self;
    _searchController.dimsBackgroundDuringPresentation = NO;
    self.definesPresentationContext = YES;
    _tableView.tableHeaderView = _searchController.searchBar;

    _searchController.searchBar.delegate = self;
    }
}

-(void)removeSearch {
    _searchController.active = NO;
    [_searchController removeFromParentViewController];
    _searchController = nil;
    _tableView.tableHeaderView = nil;
}

在 UITableView 上显示 UISearchController 向下滚动

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