iOS - UISearchBar动态搜索结果快速输入时不起作用（swift）
问题描述：
我想要的是一个搜索栏，当用户输入每个字符到搜索栏时，用户名被更新。当用户删除（退格）搜索栏中的所有字符，即搜索栏为空时，我希望tableview不显示用户名并且为空。iOS - UISearchBar动态搜索结果快速输入时不起作用（swift）
我有一个半功能的UISearchbar，用于搜索用户名（解析后端）。当我在搜索栏中逐字输入字符时，它工作的很好。
但是，当我快速输入时，搜索结果有点偏离 - 它显示了我以前输入的字符的用户名。例如：如果我很快输入'nik'，它仍然会显示我用户名'ni'。另外，当我退格时，直到搜索栏中没有字符，它仍然显示我某些用户名。
再说一次，当我慢慢输入字符时，它可以正常工作，但我觉得它效率不高。我尝试了各种各样的东西，但目前为止没有任何效果。我已经添加了下面的相关代码，让我知道你是否需要更多信息。
// called when keyboard search button pressed
func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
let searchString = searchBar.text;
if (searchString != "") {
//do load users
loadUsers(searchText: searchString!);
print("called from searchBarSearchButtonClicked");
}
}
// called when cancel button pressed
func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
searchBar.text = "";
//hide tableview maybe?!
//searchTableView.isHidden = true;
}
func updateSearchResults(for searchController: UISearchController) {
let searchString: String = (searchController.searchBar.text)!;
/*if (searchString == "" && !searchActive) {
searchResults.removeAll(keepingCapacity: false);
searchTableView.reloadData();
print("test");
}*/
if (searchString != "" && !self.searchActive) {
loadUsers(searchText: searchString);
print("called from updateResults");
}
if (searchString == "") {
searchResults.removeAll(keepingCapacity: false);
searchTableView.reloadData();
print("test");
}
}
func loadUsers(searchText: String) {
if(searchText != "") {
let usernameQuery = PFUser.query();
//usernameQuery?.whereKey("username", equalTo: searchText);
usernameQuery?.whereKey("username", contains: searchText.lowercased());
let fbUsername = PFUser.query();
fbUsername?.whereKey("username", contains: searchText);
let firstnameQuery = PFUser.query();
//firstnameQuery?.whereKey("last_name", equalTo: searchText)
firstnameQuery?.whereKey("last_name", contains: searchText);
let lastnameQuery = PFUser.query();
//lastnameQuery?.whereKey("first_name", equalTo: searchText);
lastnameQuery?.whereKey("first_name", contains: searchText);
let query = PFQuery.orQuery(withSubqueries: [usernameQuery!,fbUsername!, firstnameQuery!, lastnameQuery!]);
searchActive = true;
query.findObjectsInBackground { (objects, error) in
if error != nil {
print("There was an error getting userlist");
}
else {
if let object = objects {
self.searchResults.removeAll(keepingCapacity: false);
for object in objects! {
let user = object.object(forKey: "username") as! String;
self.searchResults.append(user);
}
//self.searchTableView.reloadData();
DispatchQueue.main.async {
self.searchTableView.reloadData();
//self.userSearchController.searchBar.resignFirstResponder();
}
}
}
self.searchActive = false;
}
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if(userSearchController.isActive) {
print(searchResults.count);
return searchResults.count;
}
return 0;
}
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath);
if(self.userSearchController.isActive && searchResults.count > indexPath.row) {
print(searchResults[indexPath.row]);
cell.textLabel?.text = searchResults[indexPath.row];
}
return cell;
}
/*
public func searchBarShouldBeginEditing(_ searchBar: UISearchBar) -> Bool {
return true;
}
public func searchBarShouldEndEditing(_ searchBar: UISearchBar) -> Bool {
return true;
}
func searchBarTextDidEndEditing(_ searchBar: UISearchBar) {
//loadUsers(searchText: (searchBar.text)!);
} */
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
if (searchBar.text != "") {
NSObject.cancelPreviousPerformRequests(withTarget: self, selector: #selector(loadUsers(searchText:)), object: searchBar.text! as String);
perform(#selector(loadUsers(searchText:)), with: searchBar.text! as String, afterDelay: 0.50);
print("called from textDidChange");
}
if (searchBar.text == "") {
searchResults.removeAll(keepingCapacity: false);
searchTableView.reloadData();
print("test2");
}
}
答
我用Timer解决了这个问题。在调用你的函数之前，下面的代码等待一秒钟。如果在那一秒内发生文本更改，则它将使先前的计划的计时器无效并且仅执行第二个计时器。您可以通过在您的功能中打印搜索文本来检查。
var timer: Timer?
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
timer?.invalidate() //cancels out previous Timers
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(myFunctionThatDoesServerSearch), userInfo: nil, repeats: false)
}