UITableView cells not showing on first load - ios

Question

My TableView Cells aren't loading, when i go to another screen and come back my data shows?
any way to fix this
my Code:
import UIKit
import FirebaseDatabase
var mynamesArray = [String]()
class Services: UIViewController, UITableViewDelegate, UITableViewDataSource {
var refHandle: UInt!
#IBOutlet var tableView: UITableView!
var videos: [String] = []
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
cell.textLabel?.text = mynamesArray[indexPath.row]
tableView.reloadData()
return cell
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
refHandle = ref.child("Services").child("ServiceA").observe(.value, with : { (snapshot) in
mynamesArray = []
for child in snapshot.children {
mynamesArray.append((child as AnyObject).key)
}
print (mynamesArray)
})
return mynamesArray.count
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == UITableViewCell.EditingStyle.delete {
mynamesArray.remove(at: indexPath.row)
tableView.reloadData()
}
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
myIndex = indexPath.row
performSegue(withIdentifier: "seque", sender: self)
}
override func viewDidLoad() {
super.viewDidLoad()
tableView.reloadData()
tableView.delegate = self
}
I am new so i don't really know how stack overflow works, do let me know if i should update anything or add anything :)
EDIT: I FORGOT TO MENTION THIS BUT I HAVE A SECOND VIEW CONTROLLER IN WHICH THE TEXT APPEARS:
import UIKit
import FirebaseDatabase
class ServicesDisplayViewController: UIViewController {
let ref = Database.database().reference()
#IBOutlet var descLabel: UILabel!
#IBOutlet var titlelabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
ref.child("ServiceC").child("Title").observeSingleEvent(of: .value, with: { DataSnapshot in
print(DataSnapshot) // replace this with textLabel or other item
})
titlelabel?.text = mynamesArray[myIndex]
descLabel?.text = descriptionList[myIndex]
// Do any additional setup after loading the view.
}

Answer 1

You are not using your numberOfRowInSection properly and are confusing sync and async programming.
numberOfRowsInSection is a synchronous method that needs to return "immediately" the number of rows for that section.
This means that you need to know how many cells are in that section in advance.
Inside of it, instead, you are using a firebase method to get that number, and that method is asynchronous. This means that when you return the number of rows it will always be 0 since the block of code you pass to the observe method will execute only after some time (the time of the http request to be made).
Another problem in your code is also the fact that you don't know how many times numberOfRowsInSection is called by the tableView, so you could end up re-making the same http request over and over (maybe not now, but in some future implementation of yours).
You should find a single place, that is maybe called only once and before the table view is shown, to call that method and fill your array before reloading the tableview.
In order to do that, you can add, in the viewDidLoad the code that handles the fetching of the array of items, than (once it's completed) you can reload the table (after you dispatch on main thread).
It would look something like this:
func viewDidLoad() {
super.viewDidLoad()
refHandle = ref.child("Services").child("ServiceA").observe(.value, with : { (snapshot) in
mynamesArray = []
for child in snapshot.children {
mynamesArray.append((child as AnyObject).key)
}
DispatchQueue.main.async {
self.tableView.reloadData()
}
})
}
And in numberOfRowsInSection you just return the count:
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) ->
return mynamesArray.count
}