我使用的是 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):
当结果为空时,
UISearchController
的viewController
仍然隐藏。这就是为什么我们必须使用 UISearchControllerDelegate
的 willPresentSearchController:
来解决问题
self.searchController
使你的ViewController符合`UISearchControllerDelegate:self.searchController.delegate = self;
willPresentSearchController:
:- (void)willPresentSearchController:(UISearchController *)searchController
{
dispatch_async(dispatch_get_main_queue(), ^{
searchController.searchResultsController.view.hidden = NO;
});
}
异步调度是必要的,因为否则它将被内部行为覆盖。您可以在这里使用动画来让表格视图淡入。
didPresentSearchController:
:- (void)didPresentSearchController:(UISearchController *)searchController
{
searchController.searchResultsController.view.hidden = NO;
}
我发现其他答案由于使用
dispatch_async
而闪烁。他们使用这个,以便在搜索控制器的内部行为完成后应用他们的更改,但这会留下几个框架,在内部行为被覆盖之前应用内部行为。使用 KVO 让我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,其他答案并没有使搜索结果控制器保持可见,这对我来说似乎是不正确的。
- (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;
}
Chris Vasselli 的答案是实现这一点的最简洁的方法。
这是 Swift 3 中的
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
}
我觉得这个方法比较好,小心searchBar为空的时候preload tableview会再次消失。
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
}
}
func willPresentSearchController(searchController: UISearchController) {
dispatch_async(dispatch_get_main_queue()) {
self.searchController.searchResultsController?.view.hidden = false
}
}
Swfit 5 版本,带有简化代码
let resultViewController = YourResultViewController()
let searchBarController = UISearchController(searchResultsController: resultViewController)
searchBarController.searchBar.delegate = resultViewController as? UISearchBarDelegate
navigationItem.searchController = searchBarController
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
if searchText.isEmpty {
DispatchQueue.main.async {
self.view.isHidden = false
}
}
}
func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
DispatchQueue.main.async {
self.view.isHidden = false
}
}