How to Update UITableView with data passed from another ViewController? - ios

Question

I am trying to populate a UITableView with data passed to the ViewController from LoginViewController after the user logs in.
The current process is:
ViewController loads first, if user is not logged in LoginViewController pops up over the top. User logs in, details are fetched from the database (userDetails and communities). LoginViewController is then dismissed and ViewController is again visible.
The communities variable is being populated and values transferred from LoginViewController to ViewController.
I believe my problem is func tableView is run before the data is fetched from the user logging in.
print ("test 1: ",communities) just prints [],[],[],[]
However print ("test 2: ",communities) prints the correct values.
import UIKit
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, UsernameSentDelegate {
#IBOutlet weak var scrollView: UIScrollView!
#IBOutlet weak var receiveUsername: UILabel!
#IBOutlet weak var userEmailText: UILabel!
var userEmail: String?
var communities = [String]()
#IBOutlet weak var communitiesTableView: UITableView!
#IBAction func unwindToHome(_ segue: UIStoryboardSegue) {
}
//recieves email address from delegate from LoginViewController
func userLoggedIn(data: String) {
userEmailText.text = data
}
override func viewDidLoad() {
super.viewDidLoad()
self.communitiesTableView.delegate = self
self.communitiesTableView.dataSource = self
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print ("test 1: ",communities) //not printing value
return self.communities.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let title = self.communities[indexPath.row]
let cell = UITableViewCell()
cell.textLabel?.text = title
return cell
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if segue.identifier == "loginView" {
let loginViewController: LoginViewController = segue.destination as! LoginViewController
loginViewController.delegate = self
}
if segue.identifier == "createCommunitySegue" {
let createCommunityController: CreateNewCommunity = segue.destination as! CreateNewCommunity
createCommunityController.myEmail = userEmailText.text
}
}
override func viewDidAppear(_ animated: Bool)
{
print ("test 2: ",communities) //prints values correctly
let isUserLoggedIn = UserDefaults.bool(UserDefaults.standard)(forKey: "isUserLoggedIn");
if(!isUserLoggedIn)
{
self.performSegue(withIdentifier: "loginView", sender: self);
}
}
#IBAction func logoutButtonTapped(_ sender: AnyObject) {
UserDefaults.set(UserDefaults.standard)(false, forKey: "isUserLoggedIn");
self.performSegue(withIdentifier: "loginView", sender: self);
}
#IBAction func createCommunityTapped(_ sender: AnyObject) {
}
}
This is the code for CreateCommunityViewController:
import UIKit
class CreateNewCommunity: UIViewController {
#IBOutlet weak var communityNameTextField: UITextField!
#IBOutlet weak var passwordTextField: UILabel!
#IBOutlet weak var emailLabel: UILabel!
var myEmail: String?
#IBAction func cancelButtonPapped(_ sender: AnyObject) {
self.performSegue(withIdentifier: "unwindCommunity", sender: self)
}
#IBAction func createCommunityButtonTapped(_ sender: AnyObject) {
let communityName = communityNameTextField.text;
if (communityName!.isEmpty){
displayMyAlertMessage(userMessage: "You must name your Community");
return;
}else{
func generateRandomStringWithLength(length: Int) -> String {
var randomString = ""
let letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
for _ in 1...length {
let randomIndex = Int(arc4random_uniform(UInt32(letters.characters.count)))
let a = letters.index(letters.startIndex, offsetBy: randomIndex)
randomString += String(letters[a])
}
return randomString
}
let communityCode = generateRandomStringWithLength(length: 6)
passwordTextField.text = communityCode
let myUrl = URL(string: "http://www.quasisquest.uk/KeepScore/createCommunity.php?");
var request = URLRequest(url:myUrl!);
request.httpMethod = "POST";
let postString = "communityname=\(communityName!)&code=\(communityCode)&email=\(myEmail!)";
request.httpBody = postString.data(using: String.Encoding.utf8);
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
DispatchQueue.main.async
{
if (try! JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? [String:AnyObject]) != nil {
let myAlert = UIAlertController(title: "Community Registered", message: "Community Code:\(communityCode)", preferredStyle: UIAlertControllerStyle.alert);
let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default){(action) in
self.dismiss(animated: true, completion: nil)
}
myAlert.addAction(okAction);
self.present(myAlert, animated: true, completion: nil)
}
}
}
task.resume()
}
}
}

Answer 1

Try to call reload data in didSet. E.g. var communities = [] { didSet { yourtableview.realoadData()
}
}