clear cache - refactor to use version numbers

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

EmployeeDirectory/SceneDelegate.swift

@@ -25,6 +25,13 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         let navigationController = UINavigationController(rootViewController: employeeListVC)
         window.rootViewController = navigationController
         
+        let appVersion = 1.5// get app version
+        let currentVersion = 1.0 //cached version
+        
+        if appVersion != currentVersion {
+            EmployeeCacheService.shared.clear()
+        }
+                
         // Set the window to the scene
         self.window = window
         window.makeKeyAndVisible()

EmployeeDirectory/Services/EmployeeCacheService.swift

@@ -0,0 +1,44 @@
+//
+//  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 {
+    // 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: cacheDirectory.appendingPathComponent("employees.json"))
+    }
+
+    public func load() throws -> Employees {
+        let data = try Data(contentsOf: cacheDirectory.appendingPathComponent("employees.json"))
+        return try JSONDecoder().decode(Employees.self, from: data)
+    }
+    
+    public func clear() {
+        try? FileManager.default.removeItem(at: cacheDirectory.appendingPathComponent("employees.json"))
+    }
+}

EmployeeDirectory/Services/EmployeeService.swift

@@ -36,8 +36,14 @@ internal enum EmployeeServiceMode: String, CaseIterable {
     }
 }
 
+
 /// Service Layer for Employees
 public class EmployeeService: EmployeeServiceProtocol {
+    public enum EmployeeServiceError: Error {
+        case error
+        //case LoadError
+        //case other(Error)
+    }
     // MARK: - Properties
     public static let shared = EmployeeService() // Default shared instance
 
@@ -51,7 +57,29 @@ public class EmployeeService: EmployeeServiceProtocol {
     /// - 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.production.endpoint, as: Employees.self)
+        var employees: Employees
+        let cache = EmployeeCacheService.shared
+        do {
+            employees = try cache.load()
+            return employees
+        } catch {
+            if let networkFound = try? await fetchNetworkEmployees() {
+                employees = networkFound
+                return employees
+            }
+        }
+        throw EmployeeServiceError.error
+    }
+    
+    public func fetchNetworkEmployees() async throws -> Employees {
+        var employees: Employees
+        if let networkFound = try? await NetworkService.shared.fetchData(from: EmployeeServiceMode.production.endpoint, as: Employees.self) {
+            employees = networkFound
+            try? EmployeeCacheService.shared.save(from: employees)
+            return employees
+        } else {
+            throw EmployeeServiceError.error
+        }
     }
 }