How can I use queryStartingAtValue in my searchcontroller to search for users?

Question

I have previously asked a question about searching for users the most cost-efficient way (without having to load up every user in the entire database.

My code before the

Answer 1

The code in the question is almost correct, just need to tweak it to ensure the enumeration var is a snapshot and then use it with Mapper.

As a user enters a user name, recursively call this with each keypress; so if they are typing in Leroy, L is typed first and this code will retrieve all nodes where the username value starts with "L". Then the user types 'e' making it 'Le' etc etc.

func searchUsers(text: String) {
    if text.count > 0 {
       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
               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

EDIT:

OP requested code for handling the search through a searchBar and a if statement to prevent searching if there are is no text. Here's the delegate method for that which calls the searchUsers function above

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

    self.searchUsers(text: searchText)
}

EDIT:

OP wanted to see my viewDidLoad function, as unexciting as it is, so here it is.

class ViewController: UIViewController, UISearchBarDelegate 
    override func viewDidLoad() {
       super.viewDidLoad()

       // Do any additional setup after loading the view.
    }

Answer 2

I am adding this as a separate answer as the OP has additional indirectly related questions:

This is my entire codebase

class ViewController: UIViewController, UISearchBarDelegate {
    @IBOutlet var searchBarOutlet: [UISearchBar]!
     override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.
        self.searchBar.delegate = self
     }

    var userNamesArray = [String]()
    func searchBar(_ searchBar: UISearchBar,
                   textDidChange searchText: String) {

        self.searchUsers(text: searchText)
    }

    func searchUsers(text: String) {
        self.userNamesArray = []
        if text.count > 0 {
            let ending = text + "\u{f8ff}"
            let databaseRef = self.ref.child("users")
            databaseRef.queryOrdered(byChild: "Name")
                .queryStarting(atValue: text)
                .queryEnding(atValue: ending)
                .observeSingleEvent(of: .value, with: { snapshot in
                    for child in snapshot.children {
                        let childSnap = child as! DataSnapshot
                        let userName = childSnap.childSnapshot(forPath: "Name").value as! String
                        self.userNamesArray.append(userName)
                    }
                    print(self.userNamesArray) //here you would call tableView.reloadData()
                })
        }
    }
}

That's it other than assigning self.ref to my Firebase. My structure is:

users
  uid_0
    name: "Frank"
  uid_1
    name: "Fred"
  uid_2
    name: "Finay"

etc when I type in the search field 'F' I get the following output

["Frank", "Fred", "Friday"]

then when I type 'Fr', I get the following output

["Frank", "Fred"]

So as you can see, it works. If it's not working in your case, you may not have your tableView connected correctly or some other issue unrelated to the search.

Now, I am not using a tableView but simply printing name strings to the console so you would need to do a tableView.reloadData() in the place of my print statement.