refactored getEmployees

Signed-off-by: Matt Bruce <mbrucedogs@gmail.com>

EmployeeDirectory/Models/Employee.swift

@@ -27,7 +27,7 @@ public enum EmployeeType: String, Codable, CustomStringConvertible {
 /// Employee Object
 /// JSON Object defintion
 /// - https://square.github.io/microsite/mobile-interview-project/
-public struct Employee: Codable {
+public struct Employee: Hashable, Codable {
     
     /// The unique identifier for the employee. Represented as a UUID.
     public let uuid: UUID

EmployeeDirectory/Protocols/EmployeeServiceProtocol.swift

@@ -10,7 +10,6 @@
 public protocol EmployeeServiceProtocol {
     
     /// This will get a list of all employees
-    /// - Parameter serviceMode: Mode in which to hit.
     /// - Returns: An Employees struct
-    func getEmployees(_ serviceMode: EmployeeServiceMode) async throws -> Employees
+    func getEmployees() async throws -> Employees
 }

EmployeeDirectory/SceneDelegate.swift

@@ -11,6 +11,25 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
 
     var window: UIWindow?
 
+    let keyAppVersion = "savedAppVersion"
+    
+    func getAppVersion() -> String {
+        if let version = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String,
+           let build = Bundle.main.infoDictionary?["CFBundleVersion"] as? String {
+            return "\(version) (\(build))"
+        }
+        return "Unknown Version"
+    }
+    
+    // Retrieve saved version
+    func getSavedAppVersion() -> String? {
+        return UserDefaults.standard.string(forKey: keyAppVersion)
+    }
+    
+    func saveAppVersion(_ version: String) {
+        UserDefaults.standard.set(version, forKey: keyAppVersion)
+        UserDefaults.standard.synchronize()
+    }
 
     func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
         
@@ -25,6 +44,19 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         let navigationController = UINavigationController(rootViewController: employeeListVC)
         window.rootViewController = navigationController
         
+        // get app version
+        let currentAppVersion = getAppVersion()
+        
+        // get app cached version
+        let savedAppVersion = getSavedAppVersion() ?? "none"
+        
+        // check to see if there is a diff and if so clear cache
+        if savedAppVersion != currentAppVersion {
+            EmployeeCacheService.shared.clear()
+            // save the current app version for next run
+            saveAppVersion(currentAppVersion)
+        }
+        
         // Set the window to the scene
         self.window = window
         window.makeKeyAndVisible()

EmployeeDirectory/Services/EmployeeCacheService.swift

@@ -0,0 +1,46 @@
+//
+//  EmployeeCacheService.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 2/6/25.
+//
+
+import Foundation
+import UIKit
+
+/// A service that handles image caching using memory, disk, and network in priority order.
+public class EmployeeCacheService {
+    private lazy var fileURL = cacheDirectory.appendingPathComponent("employees.json")
+    
+    // MARK: - Properties
+    public static let shared = EmployeeCacheService() // Default shared instance
+
+    /// Memory cache for storing images in RAM.
+    private let emplyoees: Employees? = nil
+    
+    /// File manager for handling disk operations.
+    private let fileManager = FileManager.default
+    
+    /// Directory where cached images are stored on disk.
+    private let cacheDirectory: URL = {
+        FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0]
+    }()
+    
+    // MARK: - Initializer
+    
+    public init() {}
+
+    public func save(from employees: Employees) throws {
+        let data = try JSONEncoder().encode(employees)
+        try data.write(to: fileURL)
+    }
+
+    public func load() throws -> Employees {
+        let data = try Data(contentsOf: fileURL)
+        return try JSONDecoder().decode(Employees.self, from: data)
+    }
+    
+    public func clear() {
+        try? FileManager.default.removeItem(at: fileURL)
+    }
+}

EmployeeDirectory/Services/EmployeeService.swift

@@ -7,11 +7,22 @@
 import Foundation
 
 /// These are the testing URL Endpoints for different states
-public enum EmployeeServiceMode: String, CaseIterable {
+internal enum EmployeeServiceMode: String, CaseIterable {
     case production
     case malformed
     case empty
     
+    public var service: EmployeeServiceProtocol {
+        switch self {
+        case .production:
+            return EmployeeService.shared
+        case .malformed:
+            return EmployeeMalformedService.shared
+        case .empty:
+            return EmployeeEmptyService.shared
+        }
+    }
+    
     /// Enpoint in which to grabe employees from.
     public var endpoint: String {
         switch self {
@@ -25,8 +36,10 @@ public enum EmployeeServiceMode: String, CaseIterable {
     }
 }
 
+
 /// Service Layer for Employees
 public class EmployeeService: EmployeeServiceProtocol {
+
     // MARK: - Properties
     public static let shared = EmployeeService() // Default shared instance
 
@@ -39,7 +52,59 @@ public class EmployeeService: EmployeeServiceProtocol {
     /// This will get a list of all employees
     /// - Parameter serviceMode: Mode in which to hit.
     /// - Returns: An Employees struct
-    public func getEmployees(_ serviceMode: EmployeeServiceMode = .production) async throws -> Employees {
-        return try await NetworkService.shared.fetchData(from: serviceMode.endpoint, as: Employees.self)
+    public func getEmployees() async throws -> Employees {
+        let cache = EmployeeCacheService.shared
+        
+        //try to load the employees
+        if let employees = try? cache.load() {
+            return employees
+        } else {
+            //fetch the employees
+            let employees = try await NetworkService.shared.fetchData(from: EmployeeServiceMode.production.endpoint, as: Employees.self)
+            
+            //save to cache
+            try? EmployeeCacheService.shared.save(from: employees)
+            
+            //return class
+            return employees
+        }
+    }
+}
+
+/// Service Layer for Employees
+public class EmployeeMalformedService: EmployeeServiceProtocol {
+    // MARK: - Properties
+    public static let shared = EmployeeMalformedService() // Default shared instance
+
+    // MARK: - Initializer
+
+    public init() {}
+    
+    // MARK: - Public Methods
+
+    /// This will get a list of all employees
+    /// - Parameter serviceMode: Mode in which to hit.
+    /// - Returns: An Employees struct
+    public func getEmployees() async throws -> Employees {
+        return try await NetworkService.shared.fetchData(from: EmployeeServiceMode.malformed.endpoint, as: Employees.self)
+    }
+}
+
+/// Service Layer for Employees
+public class EmployeeEmptyService: EmployeeServiceProtocol {
+    // MARK: - Properties
+    public static let shared = EmployeeEmptyService() // Default shared instance
+
+    // MARK: - Initializer
+
+    public init() {}
+    
+    // MARK: - Public Methods
+
+    /// This will get a list of all employees
+    /// - Parameter serviceMode: Mode in which to hit.
+    /// - Returns: An Employees struct
+    public func getEmployees() async throws -> Employees {
+        return try await NetworkService.shared.fetchData(from: EmployeeServiceMode.empty.endpoint, as: Employees.self)
     }
 }

EmployeeDirectory/ViewControllers/EmployeesViewController.swift

@@ -31,24 +31,46 @@ class EmployeesViewController: UIViewController {
     /// Will show specific state of the viewModel
     private var footerView: TableFooterView?
     
+    private var dataSource: UITableViewDiffableDataSource<Int, Employee>!
+
     // MARK: - Public Methods
 
     public override func viewDidLoad() {
         super.viewDidLoad()
         setupUI()
+        setupDataSource()
         bindViewModel()
         viewModel.fetchEmployees()
     }
     
     // MARK: - Private Methods
     
+    
+    /// Setup TableView dataSource
+    private func setupDataSource() {
+        dataSource = UITableViewDiffableDataSource<Int, Employee>(tableView: tableView) { tableView, indexPath, employee in
+            guard let cell = tableView.dequeueReusableCell(withIdentifier: EmployeeTableViewCell.identifier,for: indexPath) as? EmployeeTableViewCell else {
+                return UITableViewCell()
+            }
+            cell.configure(with: EmployeeCellViewModel(employee: employee))
+            return cell
+        }
+    }
+    
+    /// Snapshot Handling
+    private func applySnapshot(employees: [Employee]) {
+        var snapshot = NSDiffableDataSourceSnapshot<Int, Employee>()
+        snapshot.appendSections([0])
+        snapshot.appendItems(employees, toSection: 0)
+        dataSource.apply(snapshot, animatingDifferences: true)
+    }
+    
     /// Setup the UI by adding the views to the main view
     private func setupUI() {
         view.backgroundColor = .white
         
         // Configure TableView
         tableView.register(EmployeeTableViewCell.self, forCellReuseIdentifier: EmployeeTableViewCell.identifier)
-        tableView.dataSource = self
         view.addSubview(tableView)
         tableView.frame = view.bounds
 
@@ -70,10 +92,8 @@ class EmployeesViewController: UIViewController {
     private func bindViewModel() {
         viewModel.$employees
             .receive(on: RunLoop.main)
-            .sink { [weak self] _ in
-                self?.updateFooter()
-                self?.tableView.reloadData()
-                self?.tableView.refreshControl?.endRefreshing()
+            .sink { [weak self] employees in
+                self?.applySnapshot(employees: employees)
             }
             .store(in: &cancellables)
         
@@ -84,6 +104,8 @@ class EmployeesViewController: UIViewController {
                     self?.activityIndicator.startAnimating()
                 } else {
                     self?.activityIndicator.stopAnimating()
+                    self?.tableView.refreshControl?.endRefreshing()
+                    self?.updateFooter()
                 }
             }
             .store(in: &cancellables)
@@ -136,22 +158,6 @@ extension EmployeesViewController {
         case 2: selectedMode = .empty
         default: return
         }
-        viewModel.changeMode(to: selectedMode)
-    }
-}
-
-/// Mark: - UITableViewDataSource
-extension EmployeesViewController: UITableViewDataSource {
-    public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
-        return viewModel.employees.count
-    }
-    
-    public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
-        guard let cell = tableView.dequeueReusableCell(withIdentifier: EmployeeTableViewCell.identifier, for: indexPath) as? EmployeeTableViewCell else {
-            return UITableViewCell()
-        }
-        let employee = viewModel.employees[indexPath.row]
-        cell.configure(with: EmployeeCellViewModel(employee: employee))
-        return cell
+        viewModel.changeService(to: selectedMode.service)
     }
 }

EmployeeDirectory/ViewModels/EmployeesViewModel.swift

@@ -11,7 +11,7 @@ import Foundation
 /// specifically with the EmployeesViewController.
 @MainActor
 public class EmployeesViewModel: ObservableObject {
-    private var serviceMode: EmployeeServiceMode = .production
+    private var employeeService: EmployeeServiceProtocol = EmployeeService()
 
     @Published public private(set) var employees: [Employee] = []
     @Published public private(set) var errorMessage: String? = nil
@@ -27,7 +27,7 @@ public class EmployeesViewModel: ObservableObject {
         Task {
             do {
                 // Fetch employees using the async method
-                let wrapper = try await EmployeeService.shared.getEmployees(serviceMode)
+                let wrapper = try await employeeService.getEmployees()
                 
                 // Update published properties
                 employees = wrapper.employees
@@ -43,8 +43,8 @@ public class EmployeesViewModel: ObservableObject {
 
     }
     
-    public func changeMode(to mode: EmployeeServiceMode) {
-        serviceMode = mode
+    public func changeService(to employeeService: EmployeeServiceProtocol) {
+        self.employeeService = employeeService
         fetchEmployees()
     }
 }

EmployeeDirectory/Views/EmployeeTableViewCell.swift

@@ -128,6 +128,7 @@ public class EmployeeTableViewCell: UITableViewCell {
 
         // Bind the image to the photoImageView
         smallPhotoSubscriber = viewModel.$smallPhoto
+            .compactMap { $0 }
             .receive(on: DispatchQueue.main)
             .sink { [weak self] image in
                 self?.photoImageView.image = image