在SearchBar Tap上显示UISearchController的SearchResultsController

Question

我正在使用UISearchController而不是UISearchDisplayController，我想立即在SearchBar Tap上显示SearchResultController。现在它显示如下（当我点击搜索栏时）：

Answer 1

如果结果为空，则UISearchController＆＃39; s viewController仍然隐藏。这就是为什么我们必须使用UISearchControllerDelegate willPresentSearchController:

来摆弄我们的方式

初始化self.searchController后，使ViewController符合`UISearchControllerDelegate：

self.searchController.delegate = self;

在ViewController中实现willPresentSearchController:：

- (void)willPresentSearchController:(UISearchController *)searchController
{
    dispatch_async(dispatch_get_main_queue(), ^{
        searchController.searchResultsController.view.hidden = NO;
    });
}

异步调度是必要的，否则它将被内部行为覆盖。你可以在这里看上去并使用动画让表格视图淡入。

另外，为了理智而实施didPresentSearchController:：

- (void)didPresentSearchController:(UISearchController *)searchController
{
    searchController.searchResultsController.view.hidden = NO;
}

Answer 2

我发现其他答案因使用dispatch_async而闪烁。他们使用了这个，以便在搜索控制器的内部行为完成后应用它们的更改，但这会留下几个帧，在覆盖之前应用内部行为。使用KVO可以立即覆盖内部行为而不会出现任何闪烁。

我还发现，当用户点击ⓧ按钮清除搜索栏的内容时，其他答案并未保持搜索结果控制器可见，这对我来说似乎不正确。

- (void) viewDidLoad
{
    ...
    self.searchController.delegate = self;
    [self.searchController.searchResultsController.view addObserver:self forKeyPath:@"hidden" options:0 context:NULL];
}

- (void)observeValueForKeyPath:(NSString *)keyPath
                      ofObject:(id)object
                        change:(NSDictionary *)change
                       context:(void *)context
{    
    if ( object == self.searchController.searchResultsController.view &&
         [keyPath isEqualToString:@"hidden"] &&
         self.searchController.searchResultsController.view.hidden &&
         self.searchController.searchBar.isFirstResponder )
    {
        self.searchController.searchResultsController.view.hidden = NO;
    }
}

- (void) willPresentSearchController:(UISearchController *)searchController
{
    searchController.searchResultsController.view.hidden = NO;
}

- (void) searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
    if ( searchText.length == 0 )
        self.searchController.searchResultsController.view.hidden = NO;
}


- (void) searchBarTextDidEndEditing:(UISearchBar *)searchBar
{
    self.searchController.searchResultsController.view.hidden = YES;
}

Answer 3

Chris Vasselli的答案是实现这一目标的最简洁方法。

这里是Swift 3

override func viewDidLoad() {
    super.viewDidLoad()

    searchController.delegate = self
    self.searchController.searchResultsController?.view.addObserver(self, forKeyPath: "hidden", options: [], context: nil)
}


override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {

    if let someView: UIView = object as! UIView? {

        if (someView == self.searchController.searchResultsController?.view &&
            (keyPath == "hidden") &&
            (searchController.searchResultsController?.view.isHidden)! &&
            searchController.searchBar.isFirstResponder) {

            searchController.searchResultsController?.view.isHidden = false
        }

    }
}


func willPresentSearchController(_ searchController: UISearchController) {
    searchController.searchResultsController?.view.isHidden = false
}


func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {

    if (searchText.characters.count == 0) {
        searchController.searchResultsController?.view.isHidden = false
    }
}


func searchBarTextDidEndEditing(_ searchBar: UISearchBar) {
    searchController.searchResultsController?.view.isHidden = true
}

Answer 4

  

我认为这种方法更好，当searchBar为空时要小心，然后preload tableview会再次消失。

UISearchBarDelegate

func searchBar(searchBar: UISearchBar, textDidChange searchText: String) {
    if searchText.isEmpty {
        dispatch_async(dispatch_get_main_queue()) {
            self.searchController.searchResultsController?.view.hidden = false
        }
    }
}

func searchBarTextDidBeginEditing(searchBar: UISearchBar) {
    dispatch_async(dispatch_get_main_queue()) {
        self.searchController.searchResultsController?.view.hidden = false
    }
}

UISearchControllerDelegate

func willPresentSearchController(searchController: UISearchController) {
    dispatch_async(dispatch_get_main_queue()) {
        self.searchController.searchResultsController?.view.hidden = false
    }
}