[Feature] Location add (#11)

This PR contains the work done to add a location at a time and updates the locations in the list of locations screen right after.

To give further details about the work done:
- [x] implemented the `LocationProvider` provider in the **Persistence** library;
- [x] implemented the `SaveLocalLocationUseCase` use case;
- [x] defined the properties and functions of the `LocationsAddViewModeling` protocol to support the clean, updating and saving of locations;
- [x] implemented the `LocationsAddViewModel` view model;
- [x] implemented the `LocationsAddViewController` view controller;
- [x] implemented the dismissal of the `LocationsAddCoordinator` coordinator.

Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Reviewed-on: rock-n-code/deep-linking-assignment#11

Apps/Locations/Libraries/Sources/Persistence/Providers/LocationProvider.swift

@@ -0,0 +1,149 @@
+//
+//  LocationProvider.swift
+//  Persistence
+//
+//  Created by Javier Cicchelli on 12/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import Combine
+import CoreData
+
+public class LocationProvider: NSObject {
+    
+    // MARK: Properties
+    
+    private let fetchedResultsController: NSFetchedResultsController<Location>
+    
+    /// The publisher that emits the changes detected to the Location entities in a given object context.
+    public let didChangePublisher = PassthroughSubject<[Change], Never>()
+    
+    private var inProgressChanges: [Change] = []
+    
+    /// The number of sections in the data.
+    public var numberOfSections: Int { fetchedResultsController.sections?.count ?? 0 }
+    
+    // MARK: Initialisers
+    
+    /// Initialise this provider with the managed object context that would be used.
+    /// - Parameter managedContext: A `NSManagedObjectContext` object context instance that will be used to provide entities.
+    public init(managedContext: NSManagedObjectContext) {
+        self.fetchedResultsController = .init(
+            fetchRequest: .allLocations(),
+            managedObjectContext: managedContext,
+            sectionNameKeyPath: nil,
+            cacheName: nil
+        )
+        
+        super.init()
+        
+        self.fetchedResultsController.delegate = self
+    }
+    
+    // MARK: Functions
+    
+    /// Perform the fetching.
+    public func fetch() throws {
+        try fetchedResultsController.performFetch()
+    }
+    
+    /// Retrieve the number of locations inside a given section number.
+    /// - Parameter section: The section number to inquiry about.
+    /// - Returns: A number of locations inside the given section number.
+    public func numberOfLocationsInSection(_ section: Int) -> Int {
+        guard
+            let sections = fetchedResultsController.sections,
+            sections.endIndex > section
+        else {
+            return 0
+        }
+        
+        return sections[section].numberOfObjects
+    }
+    
+    /// Retrieve a location entity out of a given index path.
+    /// - Parameter indexPath: The index path to which retrieve a location entity.
+    /// - Returns: A `Location` entity positioned in the given index path.
+    public func location(at indexPath: IndexPath) -> Location {
+        return fetchedResultsController.object(at: indexPath)
+    }
+    
+}
+
+// MARK: - NSFetchedResultsControllerDelegate
+
+extension LocationProvider: NSFetchedResultsControllerDelegate {
+    
+    // MARK: Functions
+    
+    public func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
+        inProgressChanges.removeAll()
+    }
+    
+    public func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
+        didChangePublisher.send(inProgressChanges)
+    }
+    
+    public func controller(
+        _ controller: NSFetchedResultsController<NSFetchRequestResult>,
+        didChange sectionInfo: NSFetchedResultsSectionInfo,
+        atSectionIndex sectionIndex: Int,
+        for type: NSFetchedResultsChangeType
+    ) {
+        if type == .insert {
+            inProgressChanges.append(.section(.inserted(sectionIndex)))
+        } else if type == .delete {
+            inProgressChanges.append(.section(.deleted(sectionIndex)))
+        }
+    }
+    
+    public func controller(
+        _ controller: NSFetchedResultsController<NSFetchRequestResult>,
+        didChange anObject: Any,
+        at indexPath: IndexPath?,
+        for type: NSFetchedResultsChangeType,
+        newIndexPath: IndexPath?
+    ) {
+        switch type {
+        case .insert:
+            guard let newIndexPath else { return }
+            
+            inProgressChanges.append(.object(.inserted(at: newIndexPath)))
+        case .delete:
+            guard let indexPath else { return }
+            
+            inProgressChanges.append(.object(.deleted(from: indexPath)))
+        case .move:
+            guard let indexPath, let newIndexPath else { return }
+            
+            inProgressChanges.append(.object(.moved(from: indexPath, to: newIndexPath)))
+        case .update:
+            guard let indexPath else { return }
+            
+            inProgressChanges.append(.object(.updated(at: indexPath)))
+        default:
+            break
+        }
+    }
+    
+}
+
+// MARK: - Enumerations
+
+public enum Change: Hashable {
+    public enum SectionUpdate: Hashable {
+        case inserted(Int)
+        case deleted(Int)
+    }
+    
+    public enum ObjectUpdate: Hashable {
+        case inserted(at: IndexPath)
+        case deleted(from: IndexPath)
+        case updated(at: IndexPath)
+        case moved(from: IndexPath, to: IndexPath)
+    }
+    
+    case section(SectionUpdate)
+    case object(ObjectUpdate)
+}
+

Apps/Locations/Libraries/Sources/Remote/Models/Location.swift

@@ -16,7 +16,7 @@ public struct Location: Equatable {
     
     // MARK: Initialisers
     
-    public init(
+    init(
         name: String? = nil,
         latitude: Float,
         longitude: Float

Apps/Locations/Sources/Coordinators/LocationsAddCoordinator.swift

@@ -38,4 +38,12 @@ class LocationsAddCoordinator: Coordinator {
 
 // MARK: - LocationsAddCoordination
 
-extension LocationsAddCoordinator: LocationsAddCoordination {}
+extension LocationsAddCoordinator: LocationsAddCoordination {
+    
+    // MARK: Functions
+    
+    func closeAddLocation() {
+        router.dismiss(animated: true)
+    }
+    
+}

Apps/Locations/Sources/Protocols/Coordination/LocationsAddCoordination.swift

@@ -6,4 +6,10 @@
 //  Copyright © 2023 Röck+Cöde. All rights reserved.
 //
 
-protocol LocationsAddCoordination: AnyObject {}
+protocol LocationsAddCoordination: AnyObject {
+    
+    // MARK: Functions
+    
+    func closeAddLocation()
+    
+}

Apps/Locations/Sources/Protocols/ViewModeling/LocationsAddViewModeling.swift

@@ -6,10 +6,20 @@
 //  Copyright © 2023 Röck+Cöde. All rights reserved.
 //
 
+import Combine
+
 protocol LocationsAddViewModeling: AnyObject {
     
     // MARK: Properties
     
     var coordinator: LocationsAddCoordination? { get set }
     
+    var locationExistsPublisher: Published<Bool>.Publisher { get }
+        
+    // MARK: Functions
+    
+    func cleanLocation()
+    func saveLocation()
+    func setLocation(latitude: Float, longitude: Float)
+
 }

Apps/Locations/Sources/Protocols/ViewModeling/LocationsListViewModeling.swift

@@ -16,6 +16,7 @@ protocol LocationsListViewModeling: AnyObject {
     
     var coordinator: LocationsListCoordination? { get set }
     
+    var locationsDidChangePublisher: PassthroughSubject<[Change], Never> { get }
     var viewStatusPublisher: Published<LocationsListViewStatus>.Publisher { get }
     var numberOfSectionsInData: Int { get }
     

Apps/Locations/Sources/Screens/LocationsAdd/LocationsAddViewController.swift

@@ -6,14 +6,30 @@
 //  Copyright © 2023 Röck+Cöde. All rights reserved.
 //
 
+import Combine
 import Core
 import UIKit
+import MapKit
 
 class LocationsAddViewController: BaseViewController {
     
     // MARK: Properties
     
-    var viewModel: LocationsAddViewModeling
+    private let viewModel: LocationsAddViewModeling
+    
+    private var cancellables: Set<AnyCancellable> = []
+    
+    // MARK: Outlets
+    
+    private lazy var map = {
+        let map = MKMapView()
+
+        map.translatesAutoresizingMaskIntoConstraints = false
+        
+        map.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(tapOnMap)))
+        
+        return map
+    }()
     
     // MARK: Initialisers
     
@@ -32,7 +48,91 @@ class LocationsAddViewController: BaseViewController {
     override func viewDidLoad() {
         super.viewDidLoad()
         
-        title = "Location Add"
+        setupBar()
+        setupView()
+        bindViewModel()
+    }
+    
+}
+
+// MARK: - Helpers
+
+private extension LocationsAddViewController {
+    
+    // MARK: Functions
+    
+    func bindViewModel() {
+        viewModel
+            .locationExistsPublisher
+            .receive(on: RunLoop.main)
+            .sink { locationExists in
+                self.navigationItem
+                    .rightBarButtonItems?
+                    .forEach { $0.isEnabled = locationExists }
+            }
+            .store(in: &cancellables)
+    }
+    
+    func setupBar() {
+        title = "Add a location"
+        navigationController?.navigationBar.prefersLargeTitles = false
+        navigationController?.navigationBar.backgroundColor = .systemBackground
+        navigationController?.navigationBar.isTranslucent = true
+        navigationController?.navigationBar.tintColor = .red
+        navigationItem.rightBarButtonItems = [
+            .init(
+                title: "Save",
+                style: .plain,
+                target: self,
+                action: #selector(saveButtonPressed)
+            ),
+            .init(
+                title: "Clean",
+                style: .plain,
+                target: self,
+                action: #selector(cleanButtonPressed)
+            ),
+        ]
+    }
+    
+    func setupView() {
+        view.addSubview(map)
+                
+        NSLayoutConstraint.activate([
+            view.bottomAnchor.constraint(equalTo: map.bottomAnchor),
+            view.leadingAnchor.constraint(equalTo: map.leadingAnchor),
+            view.topAnchor.constraint(equalTo: map.topAnchor),
+            view.trailingAnchor.constraint(equalTo: map.trailingAnchor),
+        ])
+    }
+
+    // MARK: Actions
+
+    @objc func cleanButtonPressed() {
+        map.removeAnnotations(map.annotations)
+        
+        viewModel.cleanLocation()
+    }
+    
+    @objc func saveButtonPressed() {
+        viewModel.saveLocation()
+    }
+    
+    @objc func tapOnMap(recognizer: UITapGestureRecognizer) {
+        let tapOnView = recognizer.location(in: map)
+        let mapCoordinates = map.convert(tapOnView, toCoordinateFrom: map)
+        let annotation = MKPointAnnotation()
+
+        annotation.coordinate = mapCoordinates
+        
+        map.removeAnnotations(map.annotations)
+        map.addAnnotation(annotation)
+        map.setCenter(mapCoordinates, animated: true)
+        
+        viewModel.setLocation(
+            latitude: Float(mapCoordinates.latitude),
+            longitude: Float(mapCoordinates.longitude)
+        )
     }
     
 }

Apps/Locations/Sources/Screens/LocationsAdd/LocationsAddViewModel.swift

@@ -10,19 +10,82 @@ import Combine
 import Core
 
 class LocationsAddViewModel: ObservableObject {
-    
+
     // MARK: Properties
     
     weak var coordinator: LocationsAddCoordination?
     
+    @Published private var location: Location?
+    @Published private var locationExists: Bool = false
+    
+    private let saveLocalLocation = SaveLocalLocationUseCase()
+
     // MARK: Initialisers
     
     init(coordinator: LocationsAddCoordination) {
         self.coordinator = coordinator
+        
+        setupBindings()
     }
 
 }
 
 // MARK: - LocationsAddViewModeling
 
-extension LocationsAddViewModel: LocationsAddViewModeling {}
+extension LocationsAddViewModel: LocationsAddViewModeling {
+
+    // MARK: Properties
+    
+    var locationExistsPublisher: Published<Bool>.Publisher { $locationExists }
+    
+    // MARK: Functions
+    
+    func cleanLocation() {
+        location = nil
+    }
+    
+    func saveLocation() {
+        guard let location else {
+            return
+        }
+        
+        saveLocalLocation(
+            latitude: location.latitude,
+            longitude: location.longitude
+        )
+        
+        coordinator?.closeAddLocation()
+    }
+    
+    func setLocation(latitude: Float, longitude: Float) {
+        if location == nil {
+            location = .init(latitude: latitude, longitude: longitude)
+        } else {
+            location?.latitude = latitude
+            location?.longitude = longitude
+        }
+    }
+
+}
+
+// MARK: - Helpers
+
+private extension LocationsAddViewModel {
+    
+    // MARK: Functions
+    
+    func setupBindings() {
+        $location
+            .map { $0 != nil }
+            .assign(to: &$locationExists)
+    }
+}
+
+// MARK: - Structs
+
+private extension LocationsAddViewModel {
+    struct Location {
+        var latitude: Float
+        var longitude: Float
+    }
+}

Apps/Locations/Sources/Screens/LocationsList/LocationsListViewController.swift

@@ -161,6 +161,41 @@ private extension LocationsListViewController {
                 }
             }
             .store(in: &cancellables)
+        
+        viewModel
+            .controllerDidChangePublisher
+            .sink(receiveValue: { [weak self] updates in
+                var movedToIndexPaths = [IndexPath]()
+                
+                self?.table.performBatchUpdates({
+                    for update in updates {
+                        switch update {
+                        case let .section(sectionUpdate):
+                            switch sectionUpdate {
+                            case let .inserted(index):
+                                self?.table.insertSections([index], with: .automatic)
+                            case let .deleted(index):
+                                self?.table.deleteSections([index], with: .automatic)
+                            }
+                        case let .object(objectUpdate):
+                            switch objectUpdate {
+                            case let .inserted(at: indexPath):
+                                self?.table.insertRows(at: [indexPath], with: .automatic)
+                            case let .deleted(from: indexPath):
+                                self?.table.deleteRows(at: [indexPath], with: .automatic)
+                            case let .updated(at: indexPath):
+                                self?.table.reloadRows(at: [indexPath], with: .automatic)
+                            case let .moved(from: source, to: target):
+                                self?.table.moveRow(at: source, to: target)
+                                movedToIndexPaths.append(target)
+                            }
+                        }
+                    }
+                }, completion: { done in
+                    self?.table.reloadRows(at: movedToIndexPaths, with: .automatic)
+                })
+            })
+            .store(in: &cancellables)
     }
     
     @objc func addLocationPressed() {

Apps/Locations/Sources/Screens/LocationsList/LocationsListViewModel.swift

@@ -6,7 +6,6 @@
 //  Copyright © 2023 Röck+Cöde. All rights reserved.
 //
 
-import CoreData
 import Combine
 import Dependency
 import Foundation
@@ -21,16 +20,11 @@ class LocationsListViewModel: ObservableObject {
     // MARK: Properties
     
     weak var coordinator: LocationsListCoordination?
+
+    private lazy var locationProvider = LocationProvider(managedContext: persistence.container.viewContext)
     
     @Published private var viewStatus: LocationsListViewStatus = .initialised
-    
-    private lazy var fetchedResultsController = NSFetchedResultsController(
-        fetchRequest: NSFetchRequest<Location>.allLocations(),
-        managedObjectContext: persistence.container.viewContext,
-        sectionNameKeyPath: nil,
-        cacheName: nil
-    )
-    
+
     private let loadRemoteLocations = LoadRemoteLocationsUseCase()
     
     // MARK: Initialisers
@@ -44,18 +38,19 @@ class LocationsListViewModel: ObservableObject {
 // MARK: - LocationsListViewModeling
 
 extension LocationsListViewModel: LocationsListViewModeling {
-    
+
     // MARK: Properties
-    
+
+    var locationsDidChangePublisher: PassthroughSubject<[Persistence.Change], Never> { locationProvider.didChangePublisher }
+    var numberOfSectionsInData: Int { locationProvider.numberOfSections }
     var viewStatusPublisher: Published<LocationsListViewStatus>.Publisher { $viewStatus }
-    var numberOfSectionsInData: Int { fetchedResultsController.sections?.count ?? 0 }
-    
+
     // MARK: Functions
-    
+
     func openAddLocation() {
         coordinator?.openAddLocation()
     }
-    
+
     func loadLocations() {
         Task {
             do {
@@ -63,7 +58,7 @@ extension LocationsListViewModel: LocationsListViewModeling {
                 
                 try await loadRemoteLocations()
                 
-                try fetchedResultsController.performFetch()
+                try locationProvider.fetch()
 
                 viewStatus = .loaded
             } catch {
@@ -73,18 +68,11 @@ extension LocationsListViewModel: LocationsListViewModeling {
     }
     
     func numberOfDataItems(in section: Int) -> Int {
-        guard
-            let sections = fetchedResultsController.sections,
-            sections.endIndex > section
-        else {
-            return 0
-        }
-
-        return sections[section].numberOfObjects
+        locationProvider.numberOfLocationsInSection(section)
     }
     
     func dataItem(at indexPath: IndexPath) -> Location {
-        fetchedResultsController.object(at: indexPath)
+        locationProvider.location(at: indexPath)
     }
     
 }

Apps/Locations/Sources/Use Cases/LoadRemoteLocationsUseCase.swift

@@ -28,6 +28,8 @@ struct LoadRemoteLocationsUseCase {
         self.remoteService = remoteService
     }
     
+    // MARK: Functions
+    
     func callAsFunction() async throws {
         let context = persistence.makeTaskContext()
         let fetchRequest = NSFetchRequest<Persistence.Location>.allLocations()

Apps/Locations/Sources/Use Cases/SaveLocalLocationUseCase.swift

@@ -0,0 +1,54 @@
+//
+//  SaveLocalLocationUseCase.swift
+//  Locations
+//
+//  Created by Javier Cicchelli on 12/04/2023.
+//  Copyright © 2023 Röck+Cöde. All rights reserved.
+//
+
+import Dependency
+import Persistence
+
+struct SaveLocalLocationUseCase {
+    
+    // MARK: Properties
+    
+    private let persistence: PersistenceService
+    
+    // MARK: Initialisers
+    
+    init(persistence: PersistenceService) {
+        self.persistence = persistence
+    }
+    
+    // MARK: Functions
+    
+    func callAsFunction(
+        name: String? = nil,
+        latitude: Float,
+        longitude: Float
+    ) {
+        let context = persistence.makeTaskContext()
+        let entity = Location(context: context)
+        
+        entity.createdAt = .now
+        entity.name = name
+        entity.latitude = latitude
+        entity.longitude = longitude
+        entity.source = .local
+        
+        persistence.save(context: context)
+    }
+
+}
+
+// MARK: - LoadRemoteLocationsUseCase+Initialisers
+
+extension SaveLocalLocationUseCase {
+    init() {
+        @Dependency(\.persistence) var persistence
+        
+        self.init(persistence: persistence)
+    }
+}
+

DeepLinking.xcodeproj/project.pbxproj

@@ -14,6 +14,7 @@
 		02031EEA29E6B495003C108C /* ErrorMessageView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 02031EE929E6B495003C108C /* ErrorMessageView.swift */; };
 		4656CBC229E6D33C00600EE6 /* LoadRemoteLocationsUseCase.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4656CBC129E6D33C00600EE6 /* LoadRemoteLocationsUseCase.swift */; };
 		4656CBC829E6F2E400600EE6 /* LocationViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4656CBC729E6F2E400600EE6 /* LocationViewCell.swift */; };
+		4656CBE629E7360B00600EE6 /* SaveLocalLocationUseCase.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4656CBE529E7360B00600EE6 /* SaveLocalLocationUseCase.swift */; };
 		46C3B7C629E5BF1500F8F57C /* LocationsListCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46C3B7C529E5BF1500F8F57C /* LocationsListCoordinator.swift */; };
 		46C3B7CB29E5CD3200F8F57C /* LocationsListViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46C3B7CA29E5CD3200F8F57C /* LocationsListViewModel.swift */; };
 		46C3B7CF29E5D00E00F8F57C /* LocationsAddViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46C3B7CE29E5D00E00F8F57C /* LocationsAddViewModel.swift */; };
@@ -132,6 +133,7 @@
 		02031EE929E6B495003C108C /* ErrorMessageView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ErrorMessageView.swift; sourceTree = "<group>"; };
 		4656CBC129E6D33C00600EE6 /* LoadRemoteLocationsUseCase.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LoadRemoteLocationsUseCase.swift; sourceTree = "<group>"; };
 		4656CBC729E6F2E400600EE6 /* LocationViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LocationViewCell.swift; sourceTree = "<group>"; };
+		4656CBE529E7360B00600EE6 /* SaveLocalLocationUseCase.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SaveLocalLocationUseCase.swift; sourceTree = "<group>"; };
 		46C3B7C529E5BF1500F8F57C /* LocationsListCoordinator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LocationsListCoordinator.swift; sourceTree = "<group>"; };
 		46C3B7CA29E5CD3200F8F57C /* LocationsListViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LocationsListViewModel.swift; sourceTree = "<group>"; };
 		46C3B7CE29E5D00E00F8F57C /* LocationsAddViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LocationsAddViewModel.swift; sourceTree = "<group>"; };
@@ -223,6 +225,7 @@
 			isa = PBXGroup;
 			children = (
 				4656CBC129E6D33C00600EE6 /* LoadRemoteLocationsUseCase.swift */,
+				4656CBE529E7360B00600EE6 /* SaveLocalLocationUseCase.swift */,
 			);
 			path = "Use Cases";
 			sourceTree = "<group>";
@@ -544,6 +547,7 @@
 				02031EBF29E5F949003C108C /* LocationsAddViewModeling.swift in Sources */,
 				4656CBC829E6F2E400600EE6 /* LocationViewCell.swift in Sources */,
 				46C3B7DE29E5ED2E00F8F57C /* LocationsAddCoordinator.swift in Sources */,
+				4656CBE629E7360B00600EE6 /* SaveLocalLocationUseCase.swift in Sources */,
 				02031EEA29E6B495003C108C /* ErrorMessageView.swift in Sources */,
 				46C3B7DC29E5ED2300F8F57C /* LocationsAddCoordination.swift in Sources */,
 				46C3B7D829E5E55000F8F57C /* LocationsListCoordination.swift in Sources */,