How to print data in empty array

Question

I'm trying to print the chat array that is declared as a empty global variable in a table. The data that I'm trying to print is received using web sockets. I'm assigning the data in the messageReceived function, and I know that the data is getting to the program because I'm printing in a label, but the moment that I'm trying to print it in the table is simple not working. All of this is in the ViewController.swift:

import UIKit
import Starscream

var messagetext: String = ""

var tabletext: String = ""

var chat = [String] ()

class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, UITextFieldDelegate {

var socket = WebSocket(url: URL(string: "ws://localhost:1337/")!, protocols: ["chat"])

@IBOutlet weak var chatMessage: UILabel!
@IBOutlet weak var textField: UITextField!
@IBOutlet weak var tableView: UITableView!

@IBAction func buttonClick(_ sender: Any) {
    messagetext = textField.text!
    sendMessage(messagetext)
}

override func viewDidLoad() {
    super.viewDidLoad()
    self.textField.delegate = self
    socket.delegate = self
    socket.connect()
    navigationItem.hidesBackButton = true
}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    self.view.endEditing(true)
}

func textFieldDidEndEditing(_ textField: UITextField) -> Bool {
    textField.resignFirstResponder()
    return (true)
}

deinit{
    socket.disconnect(forceTimeout: 0)
    socket.delegate = nil
}
}


// MARK: - FilePrivate
fileprivate extension ViewController {

func sendMessage(_ messager: String) {

    socket.write(string: messager)
}

func messageReceived(_ message: String) {

    chatMessage.text = message
    chat.append(message)
}
}

// MARK: - WebSocketDelegate
extension ViewController : WebSocketDelegate {
public func websocketDidConnect(_ socket: Starscream.WebSocket) {

}

public func websocketDidDisconnect(_ socket: Starscream.WebSocket, error: NSError?) {
    performSegue(withIdentifier: "websocketDisconnected", sender: self)
}

public func websocketDidReceiveMessage(_ socket: Starscream.WebSocket, text: String) {
    // 1
    guard let data = text.data(using: .utf16),
        let jsonData = try? JSONSerialization.jsonObject(with: data),
        let jsonDict = jsonData as? [String: Any],
        let messageType = jsonDict["type"] as? String else {
            return
    }

    // 2
    if messageType == "message",
        let messageData = jsonDict["data"] as? [String: Any],

        let messageText = messageData["text"] as? String {

        messageReceived(messageText)


    }
}

public func websocketDidReceiveData(_ socket: Starscream.WebSocket, data: Data) {

}

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

    return(chat.count)
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier: "cell")
    cell.textLabel?.text = chat[indexPath.row] as! String

    return(cell)
}



}

Ahmad F · Accepted Answer · 2017-09-30 22:55:28Z

1

Assuming that you are sure about there is data to be received by your view controller, The issue would be: the tableview data source methods are called before receiving any data, which means chat data source array is still empty, thus there is no data to display.

The solution for your case is to make sure to reload the tableview after receiving data (updating the value of chat data source array), which means in your case after appending a message to chat in messageReceived method by calling reloadData() UITableView instance method:

func messageReceived(_ message: String) {

    chatMessage.text = message
    chat.append(message)

    // here we go:
    tableView.reloadData()
}

answered Sep 30, 2017 at 22:55

Ahmad F

31.8k19 gold badges101 silver badges151 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

ekscrypto · Accepted Answer · 2017-09-30 21:23:06Z

0

In your message received handler, issue a tableview.reloadData()

Cheers!

answered Sep 30, 2017 at 21:23

ekscrypto

3,8261 gold badge27 silver badges39 bronze badges

1 Comment

Paulw11 Over a year ago

Or preferably, call insertRows to just add the new row; reloading the whole tableview is excessive

Paulw11 · Accepted Answer · 2017-09-30 22:59:12Z

0

You need to tell the tableview that there is new data. You also need to allow for the fact that the network operation probably occurred on a background queue and UI updates must be on the main queue:

func messageReceived(_ message: String) {

    DispatchQueue.main.async {
        let newRow = IndexPath(row: chat.count, section:0)
        chatMessage.text = message
        chat.append(message)
        tableView.insertRows(at:[newRow],with: .automatic)
    }
}

answered Sep 30, 2017 at 22:59

Paulw11

116k15 gold badges175 silver badges213 bronze badges

Collectives™ on Stack Overflow

How to print data in empty array

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related