iOS dark mode status bar is not working in all view controller

Question

I do an iOS app with multiple view controller. The initial controller will show the status of current mode whereas second view is the settings.

This app has 3 options for the dark mode: Light, Dark, and System.

However, when I choose light or dark mode, the status bar color is same as the light/mode.

Eg: My system settings is in Light Mode, but I select Dark mode in the app. However, the status bar is black instead of white.

I tried many ways but it does not work, and I had deleted that code segment. Here's my code.

FirstViewController

import UIKit

class FirstViewController: UIViewController, MyDataSendingDelegate {
    var darkStatus = UserDefaults.standard.string(forKey: "dark_mode")
    
    let defaults = UserDefaults.standard
    var currentMode = UITraitCollection.current.userInterfaceStyle
    
    @IBOutlet weak var darkModeLabel: UILabel!

    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        //print(darkStatus!)
        
        if(darkStatus == "Light"){
            overrideUserInterfaceStyle = .light
            darkModeLabel.text = "Light"
        } else if (darkStatus == "Dark"){
            overrideUserInterfaceStyle = .dark
            darkModeLabel.text = "Dark"
        }else if (darkStatus == "System"){
            overrideUserInterfaceStyle = .unspecified
            darkModeLabel.text = "System"
        }
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
    }
    
    // Delegate Method
    func sendDataToFirstViewController(myData: String) {
        self.darkStatus = myData
        if(darkStatus == "Light"){
            overrideUserInterfaceStyle = .light
            currentMode = .light
            darkModeLabel.text = "Light"
        } else if (darkStatus == "Dark"){
            overrideUserInterfaceStyle = .dark
            currentMode = .dark
            darkModeLabel.text = "Dark"
        }else if (darkStatus == "System"){
            overrideUserInterfaceStyle = .unspecified
            currentMode = .unspecified
            darkModeLabel.text = "System"
        }
        
    }
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
          if segue.identifier == "darkModeSegue" {
              let secondVC = segue.destination as! DarkModeViewController
              secondVC.delegate = self
          }
    }
}

DarkModeViewController

import UIKit
protocol MyDataSendingDelegate {
    func sendDataToFirstViewController(myData: String)
}


class DarkModeViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
    
    @IBOutlet weak var darkModeTable: UITableView!
    var delegate: MyDataSendingDelegate? = nil
    
    let mode = ["Light", "Dark", "System"]
    
    let defaults = UserDefaults.standard
    var completionHandler:((String) -> Int)?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let darkStatus = defaults.string(forKey: "dark_mode")

        if(darkStatus == "Light"){
            overrideUserInterfaceStyle = .light
        } else if (darkStatus == "Dark"){
            overrideUserInterfaceStyle = .dark
        }else if (darkStatus == "System"){
            overrideUserInterfaceStyle = .unspecified
        }
        
        darkModeTable.dataSource = self
        darkModeTable.delegate = self
    }
    
    // Table View Data Source method
     func numberOfSections(in tableView: UITableView) -> Int {
        return 1
     }
    
     // Table View Data Source method
     func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return mode.count
     }

     // Table View Data Source method
     func tableView(_ tableView: UITableView,
     cellForRowAt indexPath: IndexPath)
     -> UITableViewCell {

        var cell: UITableViewCell!

         //take a cell from the queue of reusable cells
         cell = tableView.dequeueReusableCell(
         withIdentifier: "tableCell")

         //if there are no reusable cells
         if cell == nil {

             // create a new cell
             cell = UITableViewCell(
             style: UITableViewCell.CellStyle.default,
             reuseIdentifier: "tableCell")
         }

        // set the textLabel for the cell
         cell!.textLabel!.text = mode[indexPath.row]
        
        // initialize the checkmark based on Light/Dark/System
        if (overrideUserInterfaceStyle == .light){
            if (mode[indexPath.row] == "Light"){
                cell.accessoryType = .checkmark
            }
            else{
                cell.accessoryType = .none
            }
        }
        else if (overrideUserInterfaceStyle == .dark){
            if (mode[indexPath.row] == "Dark"){
                cell.accessoryType = .checkmark
            }
            else{
                cell.accessoryType = .none
            }
   
        }
        else if (overrideUserInterfaceStyle == .unspecified){
            if (mode[indexPath.row] == "System"){
                cell.accessoryType = .checkmark
            }
            else{
                cell.accessoryType = .none
            }
        }
    
         // return the Table View Cell
         return cell!
     }

    // Table View Delegate method
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        
        //clear previous stored checked indexPath
        for row in 0..<tableView.numberOfRows(inSection: indexPath.section) {
            if let cell = tableView.cellForRow(at: IndexPath(row: row, section: indexPath.section)) {
                cell.accessoryType = row == indexPath.row ? .checkmark : .none
            }
        }
        if(indexPath.row == 0)
        {
            overrideUserInterfaceStyle = .light
            defaults.setValue("Light", forKey: "dark_mode")
        }
        else if(indexPath.row == 1)
        {
            overrideUserInterfaceStyle = .dark
            defaults.setValue("Dark", forKey: "dark_mode")
        }
        else if(indexPath.row == 2)
        {
            overrideUserInterfaceStyle = .unspecified
            defaults.setValue("System", forKey: "dark_mode")
        }
        let dataToBeSent = mode[indexPath.row]
        self.delegate?.sendDataToFirstViewController(myData: dataToBeSent)
        tableView.cellForRow(at: indexPath)?.accessoryType = .checkmark
    }
    
    func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
        
        tableView.cellForRow(at: indexPath)?.accessoryType = .none
    }
    
}