Passing Data Tableview -> Viewcontroller - ios

Question

I have this tableview and I would like to pass the username to a view controller and display it there in a label, but it does not work. The username comes from a firebase database. I also checked other questions but cannot adopt it to my problem. I am not expert in coding:
import Foundation
import UIKit
import Firebase
import FirebaseDatabase
import FirebaseAuth
struct user {
let username : String!
}
class MainScreen: UITableViewController {
var Users = [user]()
override func viewDidLoad() {
let databaseRef = FIRDatabase.database().reference()
databaseRef.child("users").queryOrderedByKey()
.observe(.childAdded, with: { snapshot in
print(snapshot)
let username = (snapshot.value as? NSDictionary)!["username"] as! String
print(username)
self.Users.append(user(username: username))
self.tableView.reloadData()
print(self.Users)
})
}
override func tableView(_ tableView: UITableView,
numberOfRowsInSection section: Int) -> Int {
return Users.count
}
override func tableView(_ tableView: UITableView,
cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell")
let nameLbl = cell?.viewWithTag(1) as! UILabel
nameLbl.text = self.Users[indexPath.row].username
return cell!
}
#IBAction func ShowDetail(_ sender: Any) {
var selectedLabel:String?
func tableView(tableView: UITableView,
didSelectRowAtIndexPath indexPath: NSIndexPath) {
print("Row \(indexPath.row)selected")
selectedLabel = self.Users[indexPath.row].username
performSegue(withIdentifier: "detailView", sender: self)
}
func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "detailView") {
let vc = segue.destination as! CallDetail
vc.stringPassed = selectedLabel!
}
}
}
And the receiving ViewController looks like this:
import UIKit
class CallDetail: UIViewController {
#IBOutlet weak var UserName: UILabel!
var stringPassed = String()
override func viewDidLoad() {
super.viewDidLoad()
UserName = stringPassed.text
}
}

Answer 1

Both of didSelectRowAtIndexPath and prepareForSegue methods should be outside of #IBAction func ShowDetail(_ sender: Any) (actually, I can't figure the purpose of it):
declare selectedLabel as an instance variable and separate the methods:
import Foundation
import UIKit
import Firebase
import FirebaseDatabase
import FirebaseAuth
struct user {
let username : String!
}
class MainScreen: UITableViewController {
// 'selectedLabel' should be here:
var selectedLabel:String?
var Users = [user]()
override func viewDidLoad() {
let databaseRef = FIRDatabase.database().reference()
databaseRef.child("users").queryOrderedByKey().observe(.childAdded, with: {
snapshot in
print(snapshot)
let username = (snapshot.value as? NSDictionary)!["username"] as! String
print(username)
self.Users.append(user(username: username))
self.tableView.reloadData()
print(self.Users)
})
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return Users.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell")
let nameLbl = cell?.viewWithTag(1) as! UILabel
nameLbl.text = self.Users[indexPath.row].username
return cell!
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
print("Row \(indexPath.row)selected")
selectedLabel = self.Users[indexPath.row].username
performSegue(withIdentifier: "detailView", sender: self)
}
func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "detailView") {
let vc = segue.destination as! CallDetail
vc.stringPassed = selectedLabel!
}
}
// just remove it if you don't need it...
#IBAction func ShowDetail(_ sender: Any) {
}
}
Also, make sure that the tableView data source and delegate are connected to the viewController.

Answer 2

First you need to remove
tableView(tableView: UITableView, didSelectRowAtIndexPath because it will be called automatically when you click on a cell, if you've set the tableView delegate to the viewController.
prepareForSegue will be called after performSegue(withIdentifier: "detailView", sender: self) and delete ShowDetail(_ sender: Any) it's not necessary.
and change these lines
let nameLbl = cell?.viewWithTag(1) as! UILabel
nameLbl.text = self.Users[indexPath.row].username
to
cell.textLabel?.text = self.Users[indexPath.row].username