用户开始在搜索栏中输入内容时如何更新表视图中的信息

Question

当用户在TableView的搜索栏中键入内容时，我正在尝试自动重新加载列表。

我尝试使用下面的代码来执行此操作。我可以获取列表，但是即使我在搜索栏中键入内容，也不会“过滤”结果。

class UsersTableViewController: UITableViewController, UISearchResultsUpdating {

    func updateSearchResults(for searchController: UISearchController) {
        //update the search results
        filterContent(searchText: self.searchController.searchBar.text!)
    }


    @IBOutlet var usersTableView: UITableView!
    let searchController = UISearchController(searchResultsController: nil)

    var usersArray = [NSDictionary?]()
    var filteredUsers = [NSDictionary?]()

    var databaseRef: DatabaseReference!


    override func viewDidLoad() {
        super.viewDidLoad()

        searchController.searchResultsUpdater = self
        searchController.dimsBackgroundDuringPresentation = false
        definesPresentationContext = true

        tableView.tableHeaderView = searchController.searchBar

        databaseRef = Database.database().reference()
        let usersRef = databaseRef.child("users")
        let query = usersRef.queryOrdered(byChild: "email")
        query.observe(.childAdded, with: {(snapshot) in
            self.usersArray.append((snapshot.value as? NSDictionary?)!)

            //insert the rows
            self.usersTableView.insertRows(at: [IndexPath(row:self.usersArray.count-1, section: 0)], with: UITableView.RowAnimation.automatic)


        }) { (error) in
            print(error.localizedDescription)
        }
        print("HOLAAAAAAAAAAA")
        print(self.usersArray)

        // Uncomment the following line to preserve selection between presentations
        // self.clearsSelectionOnViewWillAppear = false

        // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
        // self.navigationItem.rightBarButtonItem = self.editButtonItem
    }

    // MARK: - Table view data source

    override func numberOfSections(in tableView: UITableView) -> Int {
        // #warning Incomplete implementation, return the number of sections
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        // #warning Incomplete implementation, return the number of rows

        if ((searchController.isActive) && (searchController.searchBar.text != "")){
            return filteredUsers.count
        }
        return self.usersArray.count
    }


    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)

        let user: NSDictionary
        if ((searchController.isActive) && (searchController.searchBar.text != "")){
            user = filteredUsers[indexPath.row]!
        }else{
            user = self.usersArray[indexPath.row]!
        }

        cell.textLabel?.text = user["email"] as? String
        cell.detailTextLabel?.text = user["name"] as? String

        return cell
    }

    func filterContent(searchText: String){
        self.filteredUsers =  self.usersArray.filter({ user in
            let userEmail = user!["email"] as? String
            return (userEmail != nil)
        })

        tableView.reloadData()
    }

    }

在用户开始键入时，我期望得到的结果是，列表应该仅显示与搜索栏中的字符串匹配的搜索。但是它没有这样做。