Implemented the BaseNavigationRouter class in the Core library.

Apps/Locations/Libraries/Sources/Core/Routers/BaseNavigationRouter.swift

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+//
+//  BaseNavigationRouter.swift
+//  Core
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import UIKit
+
+/// This is a base class for the `NavigationRouter` concrete router implementations.
+public class BaseNavigationRouter: NSObject {
+    
+    // MARK: Properties
+    
+    /// A navigation controller to use within this concrete router.
+    var navigationController: UINavigationController
+    
+    /// Dictionary that persist `onDismiss` closure for its respective view controllers until one of the later is dismissed.
+    var onDismissForViewController: [UIViewController: Router.OnDismissedClosure] = [:]
+    
+    // MARK: Initialisers
+    
+    /// Initialise this router.
+    /// - Parameter navigationController: A `UINavigationController` navigation controller instance to use in this router.
+    init(navigationController: UINavigationController) {
+        self.navigationController = navigationController
+        
+        super.init()
+        
+        self.navigationController.delegate = self
+    }
+    
+    // MARK: Functions
+    
+    /// Executes the `onDismiss` closure for a given view controller.
+    /// - Parameter viewController: A `UIViewController` view controller instance for which the on dismiss closure will be executed.
+    func performOnDismissed(for viewController: UIViewController) {
+        guard let onDismiss = onDismissForViewController[viewController] else {
+            return
+        }
+        
+        onDismiss()
+        
+        onDismissForViewController[viewController] = nil
+    }
+    
+}
+
+// MARK: - UINavigationControllerDelegate
+
+extension BaseNavigationRouter: UINavigationControllerDelegate {
+    
+    // MARK: Functions
+    
+    public func navigationController(
+        _ navigationController: UINavigationController,
+        didShow viewController: UIViewController,
+        animated: Bool
+    ) {
+        guard let dismissedViewController = navigationController.transitionCoordinator?.viewController(forKey: .from) else {
+            return
+        }
+        
+        performOnDismissed(for: dismissedViewController)
+    }
+
+}