Swift Tableview Load Data from Firebase Database - ios

Question

I am currently trying to display data from my real-time database of Firebase in different tableviews.
In my first tableview I load my first level of my database structure (this already works).
Now I want to see what the user selects in the first tableview, and then display the next level of my database in a new TableView.
I have a function in my second TableViewController.swift file where to save in the selected row from the first TableView.
This way I want to save the next level from my database into an array so that this data will be displayed in my second tableview. When I then debug my new array, I also see the correct data in the new array. However, the data is not displayed in the second TableView.
I guess it's because the data is not 100% ready before the TableView loads.
Do you have a tip?
Firebase Structure:
-sports
-Bicycle
-BMX
-Bike 1
-img: „bike1.png“
-text: „bike 1“
-Bike 2
-img: „bike2.png“
-text: „bike 1“
-Car
-Audi
-Car 1
-img: „car1.png“
-text: „car 1“
-Car 2
-img: „car2.png“
-text: „car 2“
FirstTableViewController:
import UIKit
import Firebase
class FirstTableViewController: UITableViewController {
var categorie = [String]()
func loadData() {
var ref: DatabaseReference!
ref = Database.database().reference()
ref.child("sports").observeSingleEvent(of: .value, with: { snapshot in
if let sports = snapshot.value as? [String: Any] {
for (title, _) in sports {
self.categorie.append(title)
self.tableView.reloadData()
}
}
})
}
override func viewDidLoad() {
loadData()
super.viewDidLoad()
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return categorie.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "sportCell")
cell?.textLabel?.text = categorie[indexPath.row]
return cell!
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
// Set the segue's identifier in the Storyboard
performSegue(withIdentifier: "firstToSecond", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "firstToSecond" {
guard let destination = segue.destination as? SecondTableViewController,
let indexPath = tableView.indexPathForSelectedRow else { return }
destination.detailedValue = categorie[indexPath.row]
}
}
}
SecondTableViewController:
import UIKit
import Firebase
class SecondTableViewController: UITableViewController {
var detailedValue: String?
var secondArray = [String]()
func setIndex(value: String) {
loadData(index: value)
}
func loadData(index: String) {
var ref: DatabaseReference!
ref = Database.database().reference()
if (index != "") {
ref.child("sports").child(index).observeSingleEvent(of: .value, with: { snapshot in
if let sports = snapshot.value as? [String: Any] {
for (title, _) in sports {
self.secondArray.append(title)
self.tableView.reloadData()
}
}
})
}
}
override func viewDidLoad() {
super.viewDidLoad()
if let detailedValue = detailedValue {
loadData(index: detailedValue)
}
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return secondArray.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "sorteCell")
cell?.textLabel?.text = secondArray[indexPath.row]
return cell!
}
}
UPDATE 1:
Thanks to #Jay Lee for the above code.
UPDATE 2:

Answer 1

You are not loading the data to the SecondTableViewController instance that is presented on your screen, but to a new SecondTableViewController instance that you created in the func tableView(_:=,cellForRowAt:) method in your FirstTableViewController.
The logs are printed from the multiple instances you created from it.
This is not what you want, as you are creating multiple SecondTableViewController instances every time a new cell shows in your FirstTableViewController.
You should rather get a reference to the actual SecondTableViewController that is presented and supply the data it.
If you are using a storyboard, you can use prepare(for:sender:) to do that.
We have two choices: provide the entire data from the FirstTableViewController to SecondTableViewController using a delegate design pattern, or just provide value to SecondTableViewController and leave the fetching to it.
Based on your code, you can just supply the SecondTableViewController with value that your setIndex(value:) method in the SecondTableViewController uses, and get the data after the SecondTableViewController loads.
For example, in your SecondTableViewController:
class SecondTableViewController: UITableViewController {
...
var detailedValue: String?
override func viewDidLoad() {
super.viewDidLoad()
if let detailedValue = detailedValue {
setIndex(value: detailedValue)
}
}
...
}
and in your FirstTableViewController:
class FirstTableViewController: UITableViewController {
...
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
// Set the segue's identifier in the Storyboard
performSegue(withIdentifier: "yourIdentifier", sender: self)
}
...
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "yourIdentifier" {
guard let destination = segue.destination as? SecondTableViewController,
let indexPath = tableView.indexPathForSelectedRow else { return }
destination.detailedValue = categories[indexPath.row]
}
}
}
But note that you already have a data to be shown on SecondTableViewController in your FirstTableViewController, so you should probably make a protocol and set FirstTableViewController its delegate.
EDIT:
Your segue should not be connected like this:
but like this: