Swift: numberOfRowsInSection and cellForRowAt not being invoked - ios

Question

I have been trying to display data from Firebase and display in the tableView. The data is fetched properly but is not displayed. Apart from the code mentioned below, I have already added the dataSource and Delegate for the table and the identifier for the cell.
This is the HomeTableViewController
import UIKit
import FirebaseDatabase
import Firebase
class HomeTableViewController: UITableViewController {
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
print(artists.count)
return artists.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! HomeTableViewCell
print("Here")
let artist = artists[indexPath.row]
cell.artist = artist
return cell
}
let artistRef = Database.database().reference().child("Fund")
var artists = [ArtistList]()
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
artistRef.observe(.value, with: { (snapshot) in
self.artists.removeAll()
for child in snapshot.children {
let childSnapshot = child as! DataSnapshot
let artist = ArtistList(snapshot: childSnapshot)
print(artist)
self.artists.insert(artist, at: 0)
}
self.tableView.reloadData()
})
}
override func viewDidLoad() {
super.viewDidLoad()
self.navigationController?.navigationBar.isHidden = false
self.navigationItem.hidesBackButton = true
title = "Artcall"
self.tableView.estimatedRowHeight = 290.0
self.tableView.rowHeight = UITableViewAutomaticDimension
self.tableView.reloadData()
// Uncomment the following line to preserve selection between presentations
// self.clearsSelectionOnViewWillAppear = false
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem
}
}
The main code for my HomeTableViewCell is
var artist: ArtistList!{
didSet
{
let dateString:String = String(format: "%#", artist.date as CVarArg)
labelDate.text = dateString
labelName.text = artist.name
labelLocation.text = artist.city
}
}
And the code for my model, ArtistList is here
class ArtistList
{
var name: String = ""
var city: String = ""
var date: Int64 = 0
let ref: DatabaseReference!
init(snapshot: DataSnapshot) {
ref = snapshot.ref
if let value = snapshot.value as? [String : Any] {
name = value["artist_name"] as! String
city = value["perf_location"] as! String
date = value["target_date"] as! Int64
}
}
}

Answer 1

UI updates need to occur on the main thread if they are being called within asynchronous functions, so try putting the tableview reload on the main queue like this:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
artistRef.observe(.value, with: { (snapshot) in
self.artists.removeAll()
for child in snapshot.children {
let childSnapshot = child as! DataSnapshot
let artist = ArtistList(snapshot: childSnapshot)
print(artist)
self.artists.insert(artist, at: 0)
}
//Print the artists array to verify it is definitely populated
print(self.artists)
//Reload tableview on the main queue
DispatchQueue.main.async {
self.tableView.reloadData()
}
})
}