如何在应用中搜索用户？ （最具成本效益的方式）在 Firebase

Question

我使用 firebase 制作了一个小型 MVP 测试应用。我还制作了一个用于搜索用户的 ViewController。但是现在，一旦单击 searchcontroller，我就必须加载 firebase 项目中的每个用户。这不是非常可扩展的。 （搜索控制器显示用户的用户名和个人资料照片。

我有它，所以用户必须在 searchcontroller 开始在 tableview 中显示内容之前输入至少两个单词。所以也许一个解决方案是只在点击时加载用户名，然后只在显示当前用户时加载个人资料图片？如果是这样，我该如何实现？

class FollowUsersTableViewController: UIViewController{

@IBOutlet var tableView: UITableView!

private var viewIsHiddenObserver: NSKeyValueObservation?
let searchController = UISearchController(searchResultsController: nil)
var usersArray = [UserModel]()
var filteredUsers = [UserModel]()
var loggedInUser: User?
//
var databaseRef = Database.database().reference()
//usikker på den koden over

override func viewDidLoad() {
    super.viewDidLoad()
    //large title
    self.title = "Discover"
    if #available(iOS 11.0, *) {
        self.navigationController?.navigationBar.prefersLargeTitles = true
    } else {
        // Fallback on earlier versions
    }

    self.tableView?.delegate = self
    self.tableView?.dataSource = self
    searchController.searchResultsUpdater = self
    searchController.dimsBackgroundDuringPresentation = false
    self.searchController.delegate = self;

    definesPresentationContext = true
    tableView.tableHeaderView = searchController.searchBar

    self.loadProfileData()
}

func loadProfileData() {
    databaseRef.child("profile").queryOrdered(byChild: "username").observe(.childAdded, with: { (snapshot) in
        print(snapshot)
        let userObj =  Mapper<UserModel>().map(JSONObject: snapshot.value!)
        userObj?.uid = snapshot.key

        guard snapshot.key != self.loggedInUser?.uid else { return }

        self.usersArray.append(userObj!)
    })
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    let dest = segue.destination as! UserProfileViewController
    let obj = sender as! UserModel
    let dict = ["uid": obj.uid!, "username": obj.username!, "photoURL": obj.photoURL, "bio": obj.bio]
    dest.selectedUser = dict as [String : Any]
}

  }

   // MARK: - tableview methods
   extension FollowUsersTableViewController: UITableViewDataSource, 
  UITableViewDelegate {

func tableView(_ tableView: UITableView, numberOfRowsInSection 
 section: Int) -> Int {
    return searchController.searchBar.text!.count >= 2 ? 
 filteredUsers.count : 0
  }

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

    let user = filteredUsers[indexPath.row]

    cell.title?.text = user.username
    if let url = URL(string: user.photoURL ?? "") {
        cell.userImage?.sd_setImage(with: url, placeholderImage: 
     #imageLiteral(resourceName: "user_male"), options: 
  .progressiveDownload, completed: nil)
        cell.userImage.sd_setIndicatorStyle(.gray)
        cell.userImage.sd_showActivityIndicatorView()
    }

    return cell
}

 func tableView(_ tableView: UITableView, heightForRowAt indexPath: 
   IndexPath) -> CGFloat {
    return 50
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: 
 IndexPath) {
    self.performSegue(withIdentifier: "user", sender: self.filteredUsers[indexPath.row])
}

 }

 // MARK: - search methods
 extension FollowUsersTableViewController:UISearchResultsUpdating, 
   UISearchControllerDelegate {

func updateSearchResults(for searchController: UISearchController) {
    searchController.searchResultsController?.view.isHidden = false
    filterContent(searchText: self.searchController.searchBar.text!)
    self.tableView.reloadData()
}

func filterContent(searchText:String){
    if searchText.count >= 2{
        self.filteredUsers = self.usersArray.filter{ user in
            return(user.username!.lowercased().contains(searchText.lowercased()))
        }
    }
   }
  }

Answer 1

你可以使用queryStartingAtValue:

func searchQueryUsers(text: String, completion: @escaping (_ userNames: [String]) -> Void) {

    var userNames: [String] = []

    databaseRef.child("profile").queryOrdered(byChild: "username").queryStarting(atValue: text).observeSingleEvent(of: .value, with: { snapshot in

        for item in snapshot.children {

            guard let item = item as? DataSnapshot else {
                break
            }

            //"name" is a key for name in FirebaseDatabese model
            if let dict = item.value as? [String: Any], let name = dict["name"] as? String {
                userNames.append(name)
            }
        }

        completion(userNames)
    })
}