pass two variables to the same view Controller swift - ios

Question

I want to pass two different data form two different View Controller (Table1VC - Table2VC) to one distention (MainVC)..
I did that and its worked .. but the problem is :
when I pass the first data there is no problem here
BUT the problem is when I pass the second data the first one is disappear !!
this is what I did so far :
Table1VC :
import UIKit
class Table1ViewController: UIViewController , UITableViewDelegate , UITableViewDataSource{
#IBOutlet weak var tableview: UITableView!
var city = ["data1" , "data2" , "Data3"]
var passit = ""
override func viewDidLoad() {
super.viewDidLoad()
tableview.delegate = self
tableview.dataSource = self
self.navigationController?.navigationBar.tintColor = UIColor.orange
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return city.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell()
cell.textLabel?.text = city[indexPath.row]
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
passit = city[indexPath.row]
performSegue(withIdentifier: "showtable1", sender: city[indexPath.row])
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?){
let passData1 = segue.destination as! MainVC
passData1.passcity1 = passit
}
}
Table2VC
import UIKit
class passVC: UIViewController , UITableViewDelegate , UITableViewDataSource{
#IBOutlet weak var tableView: UITableView!
var city2 = ["data1" , "data2" , "Data3"]
var passit = ""
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
self.navigationController?.navigationBar.tintColor = UIColor.orange
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return city2.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell()
cell.textLabel?.text = city2[indexPath.row]
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
passit = city2[indexPath.row]
performSegue(withIdentifier: "showtable2", sender: city2[indexPath.row])
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?){
let passData2 = segue.destination as! MainVC
passData2.passcity2 = passit
}
}
MainVC
import UIKit
class MainVC: UIViewController {
#IBOutlet weak var passText1: UITextField!
#IBOutlet weak var passText2: UITextField!
var passcity1 = ""
var passcity2 = ""
override func viewDidLoad() {
super .viewDidLoad()
passText1.text = passcity1
passText2.text = passcity2
}
}
the passed data will be in textfield in MainVC

Answer 1

This is kind of like the basics of he view stack and the life cycle of the view problem.
When you type the line:
let passData1 = segue.destination as! MainVC
it means you want to make one instance of the MainVC and want to fill up that object's data.
The instant you segue to that controller and come back to the main controller, you have lost the previous object that had the 1st value.
Example:
From VC1:
let passData1 = segue.destination as! MainVC -> means telling the compiler make me an object name "passData1", and after this any operation done on passData1 will affect passData1 only
From VC2:
let passData2 = segue.destination as! MainVC -> means telling the compiler make me an object name "passData2", and after this any operation done on passData2 will affect passData2 only.
All in all, your objects have changed, hence the previous state of the object is lost. The instant you navigate out of the MainVC for the 1st time, the next time any MainVC object is made, its a fresh copy of MainVC. You will need to set value1 and value2, both.
If you want to maintain the value of passData1, then save the required values somewhere, and when passing passData2, get those values and pass the complete set.