没有在swift中调用Self.tableView.reload数据

Question

我的self.tableView重载数据函数由于某种原因未被调用。这是我的整个tableview代码：

class NewMessageController: UITableViewController {

    let currentUser: String = (FIRAuth.auth()?.currentUser?.uid)!
    var ref = FIRDatabaseReference()
    let cellId = "cellId"
    var users = [User]()
    var groupUserArray = [GlobalVariables.UserArray]


    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.delegate = self
        tableView.dataSource = self

        getCurrentUserSchoolOrWorkAddressAndDisplayOtherUsers()

        navigationItem.title = "New Message"
        navigationItem.leftBarButtonItem = UIBarButtonItem(title: "Cancel", style: .Plain, target: self, action: #selector(cancelButton))
        navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Select", style: .Plain, target: self, action: #selector(selectButton))

//        fetchUserAndDisplay()


        tableView.registerClass(UserCell.self, forCellReuseIdentifier: cellId)
    }

    var messagesController2 = MessagingViewController?()

    func selectButton() {
        tableView.allowsMultipleSelectionDuringEditing = true
        tableView.setEditing(true, animated: false)

        if tableView.allowsMultipleSelectionDuringEditing == true  {
            navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Create", style: .Plain, target: self, action: #selector(createGroupMessagesButton))
        }

    }

    func cancelButton() {
        if tableView.allowsMultipleSelectionDuringEditing == true {
            tableView.allowsMultipleSelectionDuringEditing = false
            tableView.setEditing(false, animated: true)

            navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Select", style: .Plain, target: self, action: #selector(selectButton))
        }
        else {
            dismissViewControllerAnimated(true, completion: nil)
        }
    }

    func fetchUserAndDisplay() {
        FIRDatabase.database().reference().child("users").observeEventType(.ChildAdded, withBlock: { (snapshot) in

            if let dictionary = snapshot.value  as? [String: AnyObject] {
                let user = User()
                user.id = snapshot.key
                user.setValuesForKeysWithDictionary(dictionary)

                self.users.append(user)

                dispatch_async(dispatch_get_main_queue(), {
                    self.tableView.reloadData()
                })

            }

            }, withCancelBlock: nil)
    }

    func createGroupMessagesButton() {
        dismissViewControllerAnimated(true) {
            if let selectedUserRows = self.tableView.indexPathsForSelectedRows     {
                self.groupUserArray.append(selectedUserRows)
                for index in selectedUserRows {
                    let text = self.users[index.row]
                    self.messagesController?.showChatLogController(text)
                }
            }
        }
    }

    func getCurrentUserSchoolOrWorkAddressAndDisplayOtherUsers() {
        let currentUser = (FIRAuth.auth()?.currentUser!)
        let userID = currentUser?.uid

        FIRDatabase.database().reference().child("users").child(userID!).observeSingleEventOfType(.Value, withBlock: { (snapshot) in
            let schoolOrWorkAddress = snapshot.value!["schoolOrWorkAddress"] as! String

            FIRDatabase.database().reference().child("schoolOrWorkAddress").child(schoolOrWorkAddress).observeSingleEventOfType(.Value, withBlock: { (snapshot) in
                if(!snapshot.exists()){
                    return
                }

                let locations = snapshot.value! as! NSDictionary

                for (index, location) in locations.enumerate() {

                    FIRDatabase.database().reference().child("users").child(location.key as! String).observeEventType(.ChildAdded, withBlock: { (snapshot: FIRDataSnapshot) in
                        if(snapshot.exists()){
                            print(snapshot)
                            if let dictionary = snapshot.value  as? [String: AnyObject] {
                                let user = User()
                                user.id = snapshot.key
                                    user.setValuesForKeysWithDictionary(dictionary)

                                self.users.append(user)
                                print(self.users)

                                dispatch_async(dispatch_get_main_queue(), {
                                    self.tableView.reloadData()
                                })
                            }
                        }
                        }, withCancelBlock: nil)
                }

            })
        })
    }


    override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return users.count

    }

    var messagesController = MessagingViewController?()

    override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        if tableView.allowsMultipleSelectionDuringEditing != true {
            dismissViewControllerAnimated(true) {
                let user = self.users[indexPath.row]
                self.messagesController?.showChatLogController(user)
            }
        }

    }

    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCellWithIdentifier(cellId, forIndexPath: indexPath) as! UserCell

        let user = users[indexPath.row]

        cell.textLabel?.text = user.fullName
        cell.detailTextLabel?.text = user.email

        if let userPhoto = user.userPhoto {

            cell.profileImageView.loadImageUsingCacheWithUrlString(userPhoto)

        }

        return cell
    }


    override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
        return 72
    }

}

然而问题就出现在这里： for（index，location）in locations.enumerate（）{

                FIRDatabase.database().reference().child("users").child(location.key as! String).observeEventType(.ChildAdded, withBlock: { (snapshot: FIRDataSnapshot) in
                    if(snapshot.exists()){
                        print(snapshot)
                        if let dictionary = snapshot.value  as? [String: AnyObject] {
                            let user = User()
                            user.id = snapshot.key
                            user.setValuesForKeysWithDictionary(dictionary)

                            self.users.append(user)
                            print(self.users)

                            dispatch_async(dispatch_get_main_queue(), {
                                self.tableView.reloadData()
                            })
                        }
                    }
                    }, withCancelBlock: nil)
            }

由于某种原因，没有调用上面的reloadData函数！

以下是断点图片：

有没有人想过为什么会这样？ 任何帮助将不胜感激