[Libraries] Core (#7)

This PR contains the work that implements the Core library, which is used to define the architecture of the app.

To give further details on what was done:
- [x] created the `Core` library into the **Libraries** package;
- [x] defined the `Router` protocol;
- [x] defined the `Coordinator` protocol;
- [x] defined the `View` protocol;
- [x] defined the `ViewModel` protocol;
- [x] implemented the `NavigationRouter` router.

Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Reviewed-on: rock-n-code/deep-linking-assignment#7

Apps/Locations/Libraries/Package.swift

@@ -11,6 +11,7 @@ let package = Package(
         .library(
             name: "Libraries",
             targets: [
+                "Core",
                 "Dependency",
                 "Locations",
                 "Persistence"
@@ -23,6 +24,10 @@ let package = Package(
             name: "APICore",
             dependencies: []
         ),
+        .target(
+            name: "Core",
+            dependencies: []
+        ),
         .target(
             name: "Dependency",
             dependencies: []
@@ -43,6 +48,12 @@ let package = Package(
                 "APICore"
             ]
         ),
+        .testTarget(
+            name: "CoreTests",
+            dependencies: [
+                "Core"
+            ]
+        ),
         .testTarget(
             name: "DependencyTests",
             dependencies: [

Apps/Locations/Libraries/Sources/Core/Protocols/Coordinator.swift

@@ -0,0 +1,76 @@
+//
+//  Coordinator.swift
+//  Core
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+/// This protocol organize the flow logic between view controllers in the app.
+public protocol Coordinator: AnyObject {
+
+    // MARK: Properties
+    
+    /// The child coordinators that are being currently presented.
+    var children: [Coordinator] { get set }
+    
+    /// The router that handles how the view controllers in the coordinators will be shown or dismissed.
+    var router: Router { get }
+
+    // MARK: Functions
+    
+    /// Present the coordinator animatedly or not, dependencing on the given `animated` parameter, and also pass a closure that should be called on dismissal.
+    /// - Parameters:
+    ///   - animated: A boolean that represents whether the coordinator should be dismissed animatedly or not.
+    ///   - onDismiss: A closure to be called or executed when the presented coordinator is dismissed.
+    func present(animated: Bool, onDismiss: Router.OnDismissedClosure?)
+
+}
+
+// MARK: - Coordinator+Implementations
+
+public extension Coordinator {
+    
+    /// Present a child coordinator animatedly or not, dependencing on the given `animated` parameter, and also pass a closure that should be called on dismissal.
+    /// - Parameters:
+    ///   - child: A child coordinator to be presented.
+    ///   - animated: A boolean that represents whether the coordinator should be dismissed animatedly or not.
+    ///   - onDismiss: A closure to be called or executed when the presented coordinator is dismissed.
+    func present(
+        child: Coordinator,
+        animated: Bool,
+        onDismiss: Router.OnDismissedClosure? = nil
+    ) {
+        store(child)
+        child.present(animated: animated) { [weak self, weak child] in
+            guard let self, let child else {
+                return
+            }
+            
+            self.free(child)
+            onDismiss?()
+        }
+    }
+    
+    /// Dismiss the coordinator animatedly or not, dependencing on the given `animated` parameter.
+    /// - Parameter animated: A boolean that represents whether the coordinator should be dismissed animatedly or not.
+    func dismiss(animated: Bool) {
+        router.dismiss(animated: animated)
+    }
+
+}
+
+// MARK: - Helpers
+
+private extension Coordinator {
+    
+    // MARK: Functions
+    
+    func store(_ coordinator: Coordinator) {
+        children.append(coordinator)
+    }
+    
+    func free(_ coordinator: Coordinator) {
+        children = children.filter { $0 !== coordinator }
+    }
+}

Apps/Locations/Libraries/Sources/Core/Protocols/Router.swift

@@ -0,0 +1,55 @@
+//
+//  Router.swift
+//  Core
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import UIKit
+
+/// This protocol defines how view controllers will be shown and dismissed.
+public protocol Router: AnyObject {
+    
+    // MARK: Typealiases
+    
+    typealias OnDismissedClosure = () -> Void
+    
+    // MARK: Functions
+    
+    /// Present a view controller animatedly or not, dependencing on the given `animated` parameter, and also pass a closure that should be called on dismissal.
+    /// - Parameters:
+    ///   - viewController: A `UIViewController` view controller instance to present.
+    ///   - animated: A boolean that represents whether the view controller should be dismissed animatedly or not.
+    ///   - onDismiss: A closure to be called or executed when the presented view controller is dismissed.
+    func present(
+        _ viewController: UIViewController,
+        animated: Bool,
+        onDismiss: OnDismissedClosure?
+    )
+    
+    /// Dismiss a view controller animatedly or not, dependencing on the given `animated` parameter.
+    /// - Parameter animated: A boolean that represents whether the view controller should be dismissed animatedly or not.
+    func dismiss(animated: Bool)
+    
+}
+
+// MARK: - Router+Implementations
+
+public extension Router {
+    
+    // MARK: Functions
+    
+    /// Present a view controller animatedly or not, dependencing on the given `animated` parameter.
+    /// - Parameters:
+    ///   - viewController: A `UIViewController` view controller instance to present.
+    ///   - animated: A boolean that represents whether the view controller should be dismissed animatedly or not.
+    func present(_ viewController: UIViewController, animated: Bool) {
+        present(
+            viewController,
+            animated: animated,
+            onDismiss: nil
+        )
+    }
+
+}

Apps/Locations/Libraries/Sources/Core/Protocols/View.swift

@@ -0,0 +1,17 @@
+//
+//  View.swift
+//  Core
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+/// This protocol defines the view of the **MVVM** architecture.
+public protocol View {
+    
+    // MARK: Properties
+    
+    /// The view model related to the view.
+    var viewModel: ViewModel { get set }
+
+}

Apps/Locations/Libraries/Sources/Core/Protocols/ViewModel.swift

@@ -0,0 +1,17 @@
+//
+//  ViewModel.swift
+//  Core
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+/// This protocol defines the view model of the **MVVM** architecture.
+public protocol ViewModel: AnyObject {
+    
+    // MARK: Properties
+    
+    /// The reference to the coordinator that initialised the view model.
+    var coordinator: Coordinator { get set }
+
+}

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

@@ -0,0 +1,105 @@
+//
+//  NavigationRouter.swift
+//  Core
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import UIKit
+
+/// This class is responsible for presenting view controllers, as it is a concrete implementation of the `Router` protocol, but it won't know what view controller or which view controller is next.
+public class NavigationRouter: NSObject {
+    
+    // MARK: Properties
+    
+    /// A navigation controller to use within this concrete router.
+    private let navigationController: UINavigationController
+
+    /// A root view controller coming in from the navigation controller, if any.
+    private let rootViewController: UIViewController?
+    
+    /// Dictionary that persist `onDismiss` closure for its respective view controllers until one of the later is dismissed.
+    private var onDismissForViewController: [UIViewController: Router.OnDismissedClosure] = [:]
+
+    // MARK: Initialisers
+    
+    /// Initialise this router.
+    /// - Parameter navigationController: A `UINavigationController` navigation controller instance to use in this router.
+    public init(navigationController: UINavigationController) {
+        self.navigationController = navigationController
+        self.rootViewController = navigationController.viewControllers.first
+        
+        super.init()
+        
+        self.navigationController.delegate = self
+    }
+
+}
+
+// MARK: - Router
+
+extension NavigationRouter: Router {
+    
+    // MARK: Functions
+    
+    public func present(
+        _ viewController: UIViewController,
+        animated: Bool,
+        onDismiss: OnDismissedClosure?
+    ) {
+        onDismissForViewController[viewController] = onDismiss
+        
+        navigationController.pushViewController(viewController, animated: animated)
+    }
+    
+    public func dismiss(animated: Bool) {
+        guard let rootViewController else {
+            navigationController.popViewController(animated: animated)
+            return
+        }
+        
+        performOnDismissed(for: rootViewController)
+        
+        navigationController.popToViewController(rootViewController, animated: animated)
+    }
+    
+}
+
+// MARK: - UINavigationControllerDelegate
+
+extension NavigationRouter: 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)
+    }
+
+}
+
+// MARK: - Helpers
+
+private extension NavigationRouter {
+    
+    // MARK: Functions
+    
+    func performOnDismissed(for viewController: UIViewController) {
+        guard let onDismiss = onDismissForViewController[viewController] else {
+            return
+        }
+        
+        onDismiss()
+        
+        onDismissForViewController[viewController] = nil
+    }
+
+}

Apps/Locations/Libraries/Tests/CoreTests/Helpers/TestCoordinators.swift

@@ -0,0 +1,106 @@
+//
+//  TestCoordinators.swift
+//  CoreTests
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import Core
+import UIKit
+
+// MARK: - Test coordinators
+
+class SomeCoordinator: Coordinator {
+    
+    // MARK: Properties
+    
+    var children: [Coordinator] = []
+    var router: Router
+    
+    // MARK: Initialisers
+    
+    init(router: Router) {
+        self.router = router
+    }
+    
+    // MARK: Functions
+    
+    func present(animated: Bool, onDismiss: (() -> Void)?) {
+        router.present(
+            SomeViewController(),
+            animated: animated,
+            onDismiss: onDismiss
+        )
+    }
+
+}
+
+class SomeOtherCoordinator: Coordinator {
+
+    // MARK: Properties
+    
+    var children: [Coordinator] = []
+    var router: Router
+    
+    // MARK: Initialisers
+    
+    init(router: Router) {
+        self.router = router
+    }
+    
+    // MARK: Functions
+    
+    func present(animated: Bool, onDismiss: (() -> Void)?) {
+        router.present(
+            SomeOtherViewController(),
+            animated: animated,
+            onDismiss: onDismiss
+        )
+    }
+
+}
+
+// MARK: - SpyRouter
+
+class SpyRouter: Router {
+    
+    // MARK: Enumerations
+    
+    enum State {
+        case initialised
+        case presented
+        case dismissed
+    }
+    
+    // MARK: Properties
+    
+    var state: State = .initialised
+    var viewController: UIViewController?
+    var animated: Bool?
+    var onDismiss: OnDismissedClosure?
+    
+    // MARK: Functions
+    
+    func present(
+        _ viewController: UIViewController,
+        animated: Bool,
+        onDismiss: OnDismissedClosure?
+    ) {
+        self.viewController = viewController
+        self.animated = animated
+        self.onDismiss = onDismiss
+        self.state = .presented
+    }
+    
+    func dismiss(animated: Bool) {
+        self.animated = animated
+        self.state = .dismissed
+    }
+    
+}
+
+// MARK: - Test view controllers
+
+class SomeViewController: UIViewController {}
+class SomeOtherViewController: UIViewController {}

Apps/Locations/Libraries/Tests/CoreTests/Protocols/CoordinatorTests.swift

@@ -0,0 +1,138 @@
+//
+//  CoordinatorTests.swift
+//  CoreTests
+//
+//  Created by Javier Cicchelli on 11/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import UIKit
+import XCTest
+
+@testable import Core
+
+final class CoordinatorTests: XCTestCase {
+
+    // MARK: Properties
+    
+    private var router: SpyRouter!
+    private var coordinator: Coordinator!
+    
+    // MARK: Tests
+    
+    func test_present_withoutOnDismissClosure() {
+        // Executing this test on the main thread is required as a `UIViewController` instance in being initialised here.
+        DispatchQueue.main.async {
+            // GIVEN
+            self.router = SpyRouter()
+            self.coordinator = SomeCoordinator(router: self.router)
+            
+            
+            // WHEN
+            self.coordinator.present(animated: false, onDismiss: nil)
+            
+            // THEN
+            XCTAssertTrue(self.coordinator.children.isEmpty)
+            XCTAssertEqual(self.router.state, .presented)
+            XCTAssertTrue(self.router.viewController is SomeViewController)
+            XCTAssertFalse(self.router.animated ?? true)
+            XCTAssertNil(self.router.onDismiss)
+        }
+    }
+    
+    func test_present_withOnDismissClosure() {
+        // Executing this test on the main thread is required as a `UIViewController` instance in being initialised here.
+        DispatchQueue.main.async {
+            // GIVEN
+            self.router = SpyRouter()
+            self.coordinator = SomeOtherCoordinator(router: self.router)
+            
+            // WHEN
+            self.coordinator.present(animated: true) {}
+            
+            // THEN
+            XCTAssertTrue(self.coordinator.children.isEmpty)
+            XCTAssertEqual(self.router.state, .presented)
+            XCTAssertTrue(self.router.viewController is SomeOtherViewController)
+            XCTAssertTrue(self.router.animated ?? false)
+            XCTAssertNotNil(self.router.onDismiss)
+        }
+    }
+    
+    func test_presentChild_withoutOnDismissClosure() {
+        // Executing this test on the main thread is required as a `UIViewController` instance in being initialised here.
+        DispatchQueue.main.async {
+            // GIVEN
+            self.router = SpyRouter()
+            self.coordinator = SomeCoordinator(router: self.router)
+            
+            let child = SomeOtherCoordinator(router: self.router)
+            
+            // WHEN
+            self.coordinator.present(child: child, animated: false)
+            
+            // THEN
+            XCTAssertFalse(self.coordinator.children.isEmpty)
+            XCTAssertEqual(self.coordinator.children.count, 1)
+            XCTAssertEqual(self.router.state, .presented)
+            XCTAssertTrue(self.router.viewController is SomeOtherViewController)
+            XCTAssertFalse(self.router.animated ?? true)
+            XCTAssertNil(self.router.onDismiss)
+        }
+    }
+    
+    func test_presentChild_withOnDismissClosure() {
+        // Executing this test on the main thread is required as a `UIViewController` instance in being initialised here.
+        DispatchQueue.main.async {
+            // GIVEN
+            self.router = SpyRouter()
+            self.coordinator = SomeOtherCoordinator(router: self.router)
+            
+            let child = SomeCoordinator(router: self.router)
+            
+            // WHEN
+            self.coordinator.present(child: child, animated: true) {}
+            
+            // THEN
+            XCTAssertFalse(self.coordinator.children.isEmpty)
+            XCTAssertEqual(self.coordinator.children.count, 1)
+            XCTAssertEqual(self.router.state, .presented)
+            XCTAssertTrue(self.router.viewController is SomeViewController)
+            XCTAssertTrue(self.router.animated ?? false)
+            XCTAssertNotNil(self.router.onDismiss)
+        }
+    }
+    
+    func test_dismiss_notAnimated() {
+        // GIVEN
+        router = SpyRouter()
+        coordinator = SomeOtherCoordinator(router: router)
+        
+        // WHEN
+        coordinator.dismiss(animated: false)
+        
+        // THEN
+        XCTAssertTrue(coordinator.children.isEmpty)
+        XCTAssertEqual(router.state, .dismissed)
+        XCTAssertNil(router.viewController)
+        XCTAssertFalse(router.animated ?? true)
+        XCTAssertNil(router.onDismiss)
+    }
+    
+    func test_dismiss_animated() {
+        // GIVEN
+        router = SpyRouter()
+        coordinator = SomeOtherCoordinator(router: router)
+        
+        // WHEN
+        coordinator.dismiss(animated: true)
+        
+        // THEN
+        XCTAssertTrue(coordinator.children.isEmpty)
+        XCTAssertEqual(router.state, .dismissed)
+        XCTAssertNil(router.viewController)
+        XCTAssertTrue(router.animated ?? false)
+        XCTAssertNil(router.onDismiss)
+    }
+
+}