JoinFriendViewController.swift

import UIKit
import Firebase

protocol JoinFriendViewControllerDelegate: NSObject {
    func didJoinFriend(uid: String)
}

class JoinFriendViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

    @IBOutlet weak var tableView: UITableView!

    var userRef: DatabaseReference!
    var friendsRef: DatabaseReference!
    var resultsArray = [String]()

    var handle: AuthStateDidChangeListenerHandle?
    var currentUser: User?

    weak var delegate: JoinFriendViewControllerDelegate?

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        userRef = Database.database().reference(withPath: "users")
        friendsRef = Database.database().reference(withPath: "friends")
    }