Hi, this is my tab view controller which initialises ProfileController(...) //  MainTabBarController.swift //  AWSFullStackSocial // //  Created by Develoment on 20/07/2020. //  Copyright © 2020 Develoment. All rights reserved. // import UIKit class MainTabBarController: UITabBarController, UITabBarControllerDelegate, UINavigationControllerDelegate {          let viewModel: ViewModel          //lazy load so we can inject our viewModel     private lazy var homeController = HomeController(viewModel: self.viewModel)     private let imagePickerController = UIViewController()     lazy var profileController = ProfileController(viewModel: self.viewModel, user: self.viewModel.currentUser.value)          override func viewDidLoad() {         super.viewDidLoad()         self.delegate = self         setupComponents()     }     fileprivate func setupComponents() {                  let homeTabBarController = UINavigationController(rootViewController: self.homeController)         homeTabBarController.tabBarItem.image =  imageLiteral(resourceName: "home")                  let imagePickerTabBarController = UINavigationController(rootViewController: self.imagePickerController)         imagePickerTabBarController.tabBarItem.image =  imageLiteral(resourceName: "plus")                  let profileTabBarController = UINavigationController(rootViewController: self.profileController)         profileTabBarController.tabBarItem.image =  imageLiteral(resourceName: "home")                  self.viewControllers = [homeTabBarController, imagePickerTabBarController, profileTabBarController]     }               func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {         if self.viewControllers?.firstIndex(of: viewController) == 1 {             let imagePicker = UIImagePickerController()             imagePicker.delegate = self             self.present(imagePicker, animated: true)             return false         }          //        if self.viewControllers?.firstIndex(of: viewController) == 2 { //            if let user = self.viewModel.currentUser.value { //                self.profileController.user = user //            } //        }                  return true     }          init(viewModel: ViewModel) {         self.viewModel = viewModel         super.init(nibName: nil, bundle: nil)     }          func refreshPosts() {         self.homeController.refreshPosts()     }          required init?(coder: NSCoder) {         fatalError("init(coder:) has not been implemented")     } }

Here is my search view controller which initialises a new ProfileController(...)     func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {         let user = self.users[indexPath.row]         let controller = ProfileController(viewModel: self.viewModel, user: user, isEditable: false)         self.navigationController?.pushViewController(controller, animated: true)     } in full import JGProgressHUD import PromiseKit class SearchUserController: UIViewController, FollowUnfollowUserDelegate, UICollectionViewDelegate {          fileprivate let viewModel: ViewModel          fileprivate var users = [User]() {         didSet {             print("Users set: \(users)")             self.updateDataSourceWith(users: users)         }     }          var delegate: RefreshPostsDelegate?          enum Section: CaseIterable {         case main     }          fileprivate var collectionView: UICollectionView! = nil     fileprivate var datasource: UICollectionViewDiffableDataSource<Section, User>! = nil          override func viewDidLoad() {         super.viewDidLoad()         setupComponents()         configureDataSource()     }          override func viewWillAppear(_ animated: Bool) {         let hud = JGProgressHUD(style: .dark)         hud.textLabel.text = "Loading..."         hud.show(in: self.view)         self.viewModel.searchForUsers { result in             switch result {             case .success(let users):                 self.users = users             case .failure(let error):                 print("Error retrieving users: \(error)")             }             hud.dismiss(animated: true)                          self.viewModel.getFollowingPosts { (result) in                 switch result {                 case .success(let post):                     print(post)                 case .failure(let error):                     print("Failed to retrieve following: \(error)")                 }             }         }     }          init(viewModel: ViewModel) {         self.viewModel = viewModel         super.init(nibName: nil, bundle: nil)     }               private func createLayout() -> UICollectionViewLayout {         let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0), heightDimension: .fractionalHeight(1.0))         let item = NSCollectionLayoutItem(layoutSize: itemSize)                  let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0), heightDimension: .absolute(50))         let group = NSCollectionLayoutGroup.horizontal(layoutSize: groupSize, subitems: [item])                  let section = NSCollectionLayoutSection(group: group)                  let layout = UICollectionViewCompositionalLayout(section: section)                  return layout     }          fileprivate func setupComponents() {         self.navigationItem.title = "Search"         self.navigationController?.navigationBar.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]                  self.collectionView = UICollectionView(frame: self.view.bounds, collectionViewLayout: self.createLayout())         self.collectionView.backgroundColor = .systemBackground         self.collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight]         self.collectionView.alwaysBounceVertical = true         self.collectionView.isScrollEnabled = true         self.collectionView.register(SearchUserCell.self, forCellWithReuseIdentifier: SearchUserCell.reuseIdentifier)                  self.collectionView.delegate = self         self.view.addSubview(collectionView)     }          fileprivate func configureDataSource() {         self.datasource = UICollectionViewDiffableDataSource<Section, User>(collectionView: self.collectionView) {             (collectionView: UICollectionView, indexPath: IndexPath, user: User) -> UICollectionViewCell? in                          guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: SearchUserCell.reuseIdentifier, for: indexPath) as? SearchUserCell else { fatalError("Cannot create cell")}                          cell.nameLabel.text = self.users[indexPath.row].fullName             cell.item = user             cell.delegate = self             return cell         }     }     fileprivate func updateDataSourceWith(users: [User]) {         var snapshot = NSDiffableDataSourceSnapshot<Section, User>()         snapshot.appendSections([.main])         snapshot.appendItems(users)         self.datasource.apply(snapshot, animatingDifferences: true)     }          func handleFollow(cell: UICollectionViewCell) {         let hud = JGProgressHUD(style: .dark)         hud.textLabel.text = "Following..."         hud.show(in: self.view)         print("Handle Follow")                  guard let indexPath = self.collectionView.indexPath(for: cell) else { return }                  let user = self.users[indexPath.row]         self.viewModel.followUnfollow(user: user) { (result) in             switch result {             case .success(let user):                 self.users[indexPath.row].isFollowing = user.isFollowing                 self.delegate?.refreshPosts()                 hud.dismiss()                 self.dismiss(animated: true)             case .failure(let error):                 print("Failed to follow / unfollow user: \(error)")             }         }     }          func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {         let user = self.users[indexPath.row]         let controller = ProfileController(viewModel: self.viewModel, user: user, isEditable: false)         self.navigationController?.pushViewController(controller, animated: true)     }          required init?(coder: NSCoder) {         fatalError("init(coder:) has not been implemented")     } }

You are right, I am creating a new instance of the object, ProfileController, but I thought that it would be a self contained instance, and the existing would not be touched by the new one?