Tableviews "cellForRowAt" is never called after adding real data - ios

Question

My program is built the following:
I have a UIViewController SingleEventViewController to layout and handle data of an event. One of its elements is an UIView TeilnehmerTableView with an UITableView participantsTableView in it.
As the name says its there for displaying the users, participating at the Event. First I implemented it without "real" data. I hardcoded the users array and built the table view based on it. This worked perfectly.
But since I implemented the fetchUsers Method and filled the array with that information, the tableView does not appear at all. Obviously it doesn't display anything when I first load the page, because numberOfRowsInSection returns 0. But even after the fetch, when I reload the tableview, and the numberOfRowsInSection returns a value, the tableview is empty. While debugging I noticed that the method for populating the cells cellForRowAt never gets called. I have no clue what's going on since it all worked before using real data.
Can someone tell me what's going on?
import UIKit
import Firebase
class TeilnehmerTableView: UIView, UITableViewDelegate, UITableViewDataSource {
var parentVC: SingleEventViewController?
var users = [User]()
let participantsTableView: UITableView = {
let ctv = UITableView()
return ctv
}()
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = UIColor.green
setupTableView()
setupViews()
confBounds()
fetchUsers()
}
func setupTableView() {
participantsTableView.delegate = self
participantsTableView.dataSource = self
participantsTableView.register(TeilnehmerTVCell.self, forCellReuseIdentifier: TeilnehmerTVCell.reuseIdentifier)
participantsTableView.tintColor = .white
}
func setupViews() {
addSubview(participantsTableView)
}
func confBounds(){
participantsTableView.anchor(top: topAnchor, left: leftAnchor, bottom: bottomAnchor, right: rightAnchor, paddingTop: 0, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 0, height: 0)
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print("Users: ",users.count)
return users.count
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
print("heightForRowAt Called")
return 44
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
print("cellForRowAt Called")
let row = tableView.dequeueReusableCell(withIdentifier: TeilnehmerTVCell.reuseIdentifier, for: indexPath) as! TeilnehmerTVCell
row.user = users[indexPath.item]
return row
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: false)
}
//MARK: - Methods
func fetchUsers() {
print("Fetching users..")
let ref = Database.database().reference().child("users")
ref.observeSingleEvent(of: .value, with: { (snapshot) in
guard let dictionaries = snapshot.value as? [String: Any] else { return }
dictionaries.forEach({ (key, value) in
if key == Auth.auth().currentUser?.uid {
print("Found myself, omit from list")
return
}
guard let userDictionary = value as? [String: Any] else { return }
let user = User(uid: key, dictionary: userDictionary)
self.users.append(user)
})
self.users.sort(by: { (u1, u2) -> Bool in
return u1.username.compare(u2.username) == .orderedAscending
})
DispatchQueue.main.async( execute: {
self.participantsTableView.reloadData()
})
}) { (err) in
print("Failed to fetch users for search:", err)
}
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
This is the code for the parent the SingleEventVC:
import UIKit
import MapKit
class SingleEventViewController: UIViewController {
var thisEvent: Event
var eventName: String?
var eventDescription: String?
var eventLocation: CLLocationCoordinate2D?
var eventStartingDate: Date?
var eventFinishingDate: Date?
var eventNeedsApplication: Bool?
let padding: CGFloat = 20
//MARK: - GUI Objects
let scrollView: UIScrollView = {
let view = UIScrollView()
return view
}()
let teilnehmerLabel: UILabel = {
let label = UILabel()
label.font = UIFont.systemFont(ofSize: 20)
label.text = "Teilnehmer"
label.textColor = .black
return label
}()
let teilnehmerTV: TeilnehmerTableView = {
let tvt = TeilnehmerTableView()
tvt.backgroundColor = .brown
return tvt
}()
let buttonDividerView: UIView = {
let tdv = UIView()
tdv.backgroundColor = UIColor.gray
return tdv
}()
let participateButton: UIButton = {
let button = UIButton()
button.backgroundColor = CalendarSettings.Colors.buttonBG
button.setTitle("Teilnehmen", for: .normal)
button.setTitleColor(CalendarSettings.Colors.darkRed, for: .normal)
return button
}()
init(event: Event) {
thisEvent = event
super.init(nibName: nil, bundle: nil)
setupDefaultValues()
}
override func viewDidLoad() {
super.viewDidLoad()
applyDefaultValues()
setupNavBar()
setupViews()
confBounds()
getSnapshotForLocation()
}
//MARK: - Setup
func setupDefaultValues() {
eventName = thisEvent.eventName
eventDescription = thisEvent.eventDescription
eventLocation = thisEvent.eventLocation
eventStartingDate = thisEvent.eventStartingDate
eventFinishingDate = thisEvent.eventFinishingDate
eventNeedsApplication = thisEvent.eventNeedsApplication
}
func applyDefaultValues() {
titleLabel.text = eventName
descLabel.text = eventDescription
if let start = eventStartingDate, let finish = eventFinishingDate {
timeLabel.text = "Von \(start.getHourAndMinuteAsStringFromDate()) bis \(finish.getHourAndMinuteAsStringFromDate())"
}
if let location = eventLocation {
locationLabel.text = getStringFromLocation(location: location)
mapLabel.text = getStringFromLocation(location: location)
}
if let date = eventStartingDate {
dateLabel.text = formatDate(date: date)
}
}
func setupNavBar() {
self.navigationItem.title = "Event"
}
func setupViews() {
view.addSubview(scrollView)
view.addSubview(participateButton)
participateButton.addTarget(self, action: #selector (buttonClick), for: .touchUpInside)
view.addSubview(buttonDividerView)
scrollView.addSubview(teilnehmerLabel)
scrollView.addSubview(teilnehmerTV)
teilnehmerTV.parentVC = self
}
func confBounds(){
let tabbarHeight = self.tabBarController?.tabBar.frame.height ?? 0
let tableviewHeight: CGFloat = CGFloat(teilnehmerTV.users.count) * 44
participateButton.anchor(top: nil, left: view.leftAnchor, bottom: view.bottomAnchor, right: view.rightAnchor, paddingTop: 0, paddingLeft: 0, paddingBottom: tabbarHeight, paddingRight: 0, width: 0, height: 50)
buttonDividerView.anchor(top: nil, left: view.leftAnchor, bottom: participateButton.topAnchor, right: view.rightAnchor, paddingTop: 0, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 0, height: 0.5)
scrollView.anchor(top: view.topAnchor, left: view.leftAnchor, bottom: buttonDividerView.topAnchor, right: view.rightAnchor, paddingTop: 0, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 0, height: 0)
teilnehmerLabel.anchor(top: descLabel.bottomAnchor, left: view.leftAnchor, bottom: nil, right: view.rightAnchor, paddingTop: 20, paddingLeft: padding, paddingBottom: 0, paddingRight: padding, width: 0, height: 0)
teilnehmerTV.anchor(top: teilnehmerLabel.bottomAnchor, left: view.leftAnchor, bottom: scrollView.bottomAnchor, right: view.rightAnchor, paddingTop: 5, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 0, height: tableviewHeight)
}
override func viewDidLayoutSubviews() {
let objHeight = titleLabel.frame.height + locationLabel.frame.height + dateLabel.frame.height + timeLabel.frame.height + mapView.frame.height + notizenLabel.frame.height + descLabel.frame.height + teilnehmerLabel.frame.height + teilnehmerTV.frame.height
let paddingHeight = 10+0+50+padding+20+5 - 15
print(objHeight, paddingHeight)
scrollView.contentSize = CGSize(width: view.frame.width, height: objHeight+paddingHeight)
}
//MARK: - Methods
#objc func buttonClick() {
teilnehmerTV.participantsTableView.reloadData()
print(teilnehmerTV.participantsTableView.numberOfRows(inSection: 0))
scrollView.reloadInputViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}

Answer 1

It's because you have not added TeilnehmerTableView to the view in SingleEventViewController when you make the fetch request - you make the request during initialization of TeilnehmerTableView. Try calling fetchUsers from SingleEventViewController after you have added TeilnehmerTableView to the view; it should then work.