Question

仅当用户键入至少2个单词时，我才尝试完成对其他用户的搜索，然后才开始在数据库中搜索（因为我不想为用户扫描整个数据库）。我在使用2个字母进行搜索时遇到了一些问题，但是我想我已经得到了代码（感谢用户Jay）。

但是，当我在模拟器中运行它时，控制台会打印名称，但是在表视图中什么都没显示？（其为空）。

你知道我做错了吗？

这是我的代码：

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()

        searchController.searchBar.delegate = self


        //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



    }

    func searchUsers(text: String) {
        if text.count >= 2 {
            self.usersArray = [] //clear the array each time
            let endingText = text + "\u{f8ff}"
            databaseRef.child("profile").queryOrdered(byChild: "username")
                .queryStarting(atValue: text)
                .queryEnding(atValue: endingText)
                .observeSingleEvent(of: .value, with: { snapshot in

                    for child in snapshot.children {
                        let childSnap = child as! DataSnapshot
                        print(childSnap)
                        let userObj =  Mapper<UserModel>().map(JSONObject: childSnap.value!)
                        userObj?.uid = childSnap.key
                        if childSnap.key != self.loggedInUser?.uid { //ignore this user
                            self.usersArray.append(userObj!)

                        }
                    }
                    self.tableView.reloadData()
                })
        }
    } //may need an else statement here to clear the array when there is no text


    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, UISearchBarDelegate {



    func updateSearchResults(for searchController: UISearchController) {
        searchController.searchResultsController?.view.isHidden = false

        self.searchUsers(text: self.searchController.searchBar.text!)

        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

This code is very close, and as the other answer points out you've got two arrays.

But let's really simplify the issue: You only need one array since you are filtering Firebase, not the array.

In other words when a user types into the searchField, you're querying Firebase for results and putting them into an array. That's the same array you should be using as the dataSource for your tableView.

As your code sits, you're filtering Firebase and then filtering those results again which isn't needed.

So at a high level supposed we have four users in our database

Larry
Moe
Monroe
Curly

the user types 'Mo' into the search field which causes your Fire query to execute. It will return two results:

Mo
Monroe

which then gets populated into an array - we'll call it userResultsArray.

then

tableView.reloadData()

which then calls the tableView delegate methods

func tableView(_ tableView: UITableView, numberOfRowsInSection
   return userResultsArray.count

and

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath)
   get the user from userResultsArray
   return the user name

As shown, you only need the single array to store the queried (filtered) results from Firebase.

Answer 2

您有2个数组usersArray和filteredUsers

if childSnap.key != self.loggedInUser?.uid { //ignore this user
       self.usersArray.append(userObj!)
}
...
 self.tableView.reloadData()

因此上述重新加载不会像您一直使用的那样起作用

let user = filteredUsers[indexPath.row]

在cellForRowAt中，在这种情况下，您应该使用var

var isSearching = false

，然后在所有委托和dataSource方法中进行搜索时进行更改

 func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return isSearching ? filteredUsers.count : usersArray.count
 }
 func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! FollowTableViewCell

    let user = isSearching ? filteredUsers[indexPath.row] : usersArray[indexPath.row] 
  .....
 }

func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
    isSearching = true
}

func searchBarTextDidEndEditing(_ searchBar: UISearchBar) {
    isSearching = false
}

func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
    isSearching = false
}

func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
    isSearching = false
}

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

    filteredUsers = usersArray.filter { /* do filter */ }

    if(filteredUsers.count == 0){
        isSearching = false
    } else {
        isSearching = true
    }
    self.tableView.reloadData()
}

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

为什么我的tableview显示搜索结果？

2 个答案: