forgot a hashvalue always changes so I can't use that, therefore I created extension on URL for a UniqueIdentifier based of crypto that will always be the same.

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

EmployeeDirectory/Extensions/URL.swift

@@ -0,0 +1,16 @@
+//
+//  URL.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+import Foundation
+import CryptoKit
+
+extension URL {
+    internal var uniqueIdentifier: String {
+        let data = Data(absoluteString.utf8)
+        let hash = SHA256.hash(data: data)
+        return hash.compactMap { String(format: "%02x", $0) }.joined()
+    }
+}

EmployeeDirectory/Models/Employee.swift

@@ -0,0 +1,70 @@
+//
+//  Employee.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+
+import Foundation
+
+/// EmployeeType enum
+/// - How the employee is classified.
+public enum EmployeeType: String, Codable, CustomStringConvertible {
+    case fullTime = "FULL_TIME"
+    case partTime = "PART_TIME"
+    case contractor = "CONTRACTOR"
+    
+    /// Format the employee type for display
+    public var description: String {
+        switch self {
+        case .fullTime: return "Full-Time"
+        case .partTime: return "Part-Time"
+        case .contractor: return "Contractor"
+        }
+    }
+}
+
+/// Employee Object
+/// JSON Object defintion
+/// - https://square.github.io/microsite/mobile-interview-project/
+public struct Employee: Codable {
+    
+    /// The unique identifier for the employee. Represented as a UUID.
+    public let uuid: UUID
+    
+    /// The full name of the employee.
+    public let fullName: String
+    
+    /// The phone number of the employee, sent as an unformatted string (eg, 5556661234).
+    public let phoneNumber: String?
+    
+    /// The email address of the employee.
+    public let emailAddress: String
+    
+    /// A short, tweet-length (~300 chars) string that the employee provided to describe themselves.
+    public let biography: String?
+    
+    /// The URL of the employee’s small photo. Useful for list view.
+    public let photoURLSmall: String?
+    
+    /// The URL of the employee’s full-size photo.
+    public let photoURLLarge: String?
+    
+    /// The team they are on, represented as a human readable string.
+    public let team: String
+    
+    /// How the employee is classified.
+    public let employeeType: EmployeeType
+    
+    private enum CodingKeys: String, CodingKey {
+        case uuid
+        case fullName = "full_name"
+        case phoneNumber = "phone_number"
+        case emailAddress = "email_address"
+        case biography
+        case photoURLSmall = "photo_url_small"
+        case photoURLLarge = "photo_url_large"
+        case team
+        case employeeType = "employee_type"
+    }
+}

EmployeeDirectory/Models/Employees.swift

@@ -0,0 +1,16 @@
+//
+//  Employees.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+import Foundation
+
+/// Wrapper JSON Class for the Employees
+public struct Employees: Codable {
+    public var employees: [Employee]
+    
+    private enum CodingKeys: String, CodingKey {
+        case employees
+    }
+}

EmployeeDirectory/Protocols/EmployeeServiceProtocol.swift

@@ -0,0 +1,10 @@
+//
+//  EmployeeServiceable.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+
+public protocol EmployeeServiceProtocol {
+    func getEmployees(_ serviceMode: EmployeeServiceMode) async throws -> Employees
+}

EmployeeDirectory/Services/EmployeeService.swift

@@ -0,0 +1,37 @@
+//
+//  EmployeeService.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+import Foundation
+
+/// These are the testing URL Endpoints for different states
+public enum EmployeeServiceMode: String, CaseIterable {
+    case production
+    case malformed
+    case empty
+    
+    public var endpoint: String {
+        switch self {
+        case .production:
+            return "https://s3.amazonaws.com/sq-mobile-interview/employees.json"
+        case .malformed:
+            return "https://s3.amazonaws.com/sq-mobile-interview/employees_malformed.json"
+        case .empty:
+            return "https://s3.amazonaws.com/sq-mobile-interview/employees_empty.json"
+        }
+    }
+}
+
+/// Service Layer for Employees
+public class EmployeeService: EmployeeServiceProtocol {
+    
+    public init() {}
+    
+    /// Service to get Employees
+    /// - Returns: Array of Employee Structs
+    public func getEmployees(_ serviceMode: EmployeeServiceMode = .production) async throws -> Employees {
+        return try await NetworkService.shared.fetchData(from: serviceMode.endpoint, as: Employees.self)
+    }
+}

EmployeeDirectory/Services/ImageCacheService.swift

@@ -0,0 +1,58 @@
+//
+//  ImageCacheService.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+
+import Foundation
+import UIKit
+
+public class ImageCacheService {
+    public static let shared = ImageCacheService() // Default shared instance
+
+    private let memoryCache = NSCache<NSString, UIImage>()
+    private let fileManager = FileManager.default
+    private let cacheDirectory: URL = {
+       FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0]
+    }()
+    
+    public init() {}
+
+    public func loadImage(from url: URL) async -> UIImage? {
+        let uniqueKey = url.uniqueIdentifier
+        let cacheKey = uniqueKey as NSString
+    
+        if let cachedImage = memoryCache.object(forKey: cacheKey) {
+            return cachedImage
+        }
+        
+        let diskImagePath = cacheDirectory.appendingPathComponent(uniqueKey)
+        if let diskImage = UIImage(contentsOfFile: diskImagePath.path) {
+            memoryCache.setObject(diskImage, forKey: cacheKey)
+            return diskImage
+        }
+        
+        if let networkImage = await fetchFromNetwork(url: url) {
+            memoryCache.setObject(networkImage, forKey: cacheKey)
+            try? saveImageToDisk(image: networkImage, at: diskImagePath)
+            return networkImage
+        }
+        
+        return nil
+    }
+    
+    private func fetchFromNetwork(url: URL) async -> UIImage? {
+        do {
+            let (data, _) = try await URLSession.shared.data(from: url)
+            return UIImage(data: data)
+        } catch {
+            return nil
+        }
+    }
+    
+    private func saveImageToDisk(image: UIImage, at path: URL) throws {
+        guard let data = image.pngData() else { return }
+        try data.write(to: path)
+    }
+}

EmployeeDirectory/ViewControllers/EmployeesViewController.swift

@@ -6,14 +6,124 @@
 //
 
 import UIKit
+import Combine
 
 class EmployeesViewController: UIViewController {
-
-    override func viewDidLoad() {
+    private let tableView = UITableView()
+    private let activityIndicator = UIActivityIndicatorView(style: .large)
+    private let modeSegmentedControl = UISegmentedControl(items: EmployeeServiceMode.allCases.map{ $0.rawValue } )
+    private let viewModel = EmployeesViewModel()
+    private var cancellables = Set<AnyCancellable>()
+    private var footerView: TableFooterView?
+    
+    public override func viewDidLoad() {
         super.viewDidLoad()
-        // Do any additional setup after loading the view.
+        setupUI()
+        bindViewModel()
+        viewModel.fetchEmployees()
     }
+    
+    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
 
+        //add pull to refresh
+        tableView.refreshControl = UIRefreshControl()
+        tableView.refreshControl?.addTarget(self, action: #selector(didPullToRefresh), for: .valueChanged)
+        
+        // Configure Activity Indicator
+        activityIndicator.center = view.center
+        view.addSubview(activityIndicator)
 
+        // Configure Mode Selector
+        modeSegmentedControl.selectedSegmentIndex = 0
+        modeSegmentedControl.addTarget(self, action: #selector(onServiceModeChange), for: .valueChanged)
+        navigationItem.titleView = modeSegmentedControl
+    }
+    
+    private func bindViewModel() {
+        viewModel.$employees
+            .receive(on: RunLoop.main)
+            .sink { [weak self] _ in
+                self?.updateFooter()
+                self?.tableView.reloadData()
+                self?.tableView.refreshControl?.endRefreshing()
+            }
+            .store(in: &cancellables)
+        
+        viewModel.$isLoading
+            .receive(on: RunLoop.main)
+            .sink { [weak self] isLoading in
+                if isLoading {
+                    self?.activityIndicator.startAnimating()
+                } else {
+                    self?.activityIndicator.stopAnimating()
+                }
+            }
+            .store(in: &cancellables)
+        
+        viewModel.$errorMessage
+            .receive(on: RunLoop.main)
+            .sink { [weak self] _ in
+                self?.updateFooter()
+            }
+            .store(in: &cancellables)
+    }
+        
+    private func updateFooter() {
+        var message: String? {
+            guard !viewModel.isLoading else { return nil }
+            return viewModel.errorMessage ?? (viewModel.employees.isEmpty ? "No employees found, please try to refresh." : nil)
+        }
+        
+        if let message, !viewModel.isLoading {
+            // Lazy initialize footerView if needed
+            if footerView == nil {
+                footerView = TableFooterView(message: message)
+            } else { // Update the message
+                footerView?.update(message: message)
+            }
+            footerView?.frame = CGRect(x: 0, y: 0, width: tableView.frame.width, height: 150)
+            tableView.tableFooterView = footerView
+        } else {
+            tableView.tableFooterView = nil
+        }
+    }
 }
 
+extension EmployeesViewController {
+    @objc private func didPullToRefresh() {
+        viewModel.fetchEmployees()
+    }
+    
+    @objc private func onServiceModeChange(_ sender: UISegmentedControl) {
+        let selectedMode: EmployeeServiceMode
+        switch sender.selectedSegmentIndex {
+        case 0: selectedMode = .production
+        case 1: selectedMode = .malformed
+        case 2: selectedMode = .empty
+        default: return
+        }
+        viewModel.changeMode(to: selectedMode)
+    }
+}
+
+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
+    }
+}

EmployeeDirectory/ViewModels/EmployeeCellViewModel.swift

@@ -0,0 +1,44 @@
+//
+//  EmployeeCellViewModel.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+
+import Foundation
+import UIKit
+
+@MainActor
+public class EmployeeCellViewModel: ObservableObject {
+    private let employee: Employee
+    
+    public private(set) var uuid: String
+    public private(set) var fullName: String
+    public private(set) var phoneNumber: String?
+    public private(set) var emailAddress: String
+    public private(set) var biography: String?
+    public private(set) var team: String
+    public private(set) var employeeType: String
+    @Published public private(set) var smallPhoto: UIImage?
+    
+    public init(employee: Employee) {
+        self.employee = employee
+        
+        // Initialize properties
+        self.uuid = employee.uuid.uuidString
+        self.fullName = employee.fullName
+        self.phoneNumber = employee.phoneNumber
+        self.emailAddress = employee.emailAddress
+        self.biography = employee.biography
+        self.team = employee.team
+        self.employeeType = employee.employeeType.description
+        
+        if let endpoint = employee.photoURLSmall {
+            Task{
+                if let smallPhotoURL = URL(string: endpoint) {
+                    smallPhoto = await ImageCacheService.shared.loadImage(from: smallPhotoURL)
+                }
+            }
+        }
+    }
+}

EmployeeDirectory/ViewModels/EmployeesViewModel.swift

@@ -0,0 +1,52 @@
+//
+//  EmployeesViewModel.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+
+import Foundation
+
+@MainActor
+public class EmployeesViewModel: ObservableObject {
+    private let service: EmployeeService
+    private var serviceMode: EmployeeServiceMode = .production
+
+    @Published public private(set) var employees: [Employee] = []
+    @Published public private(set) var errorMessage: String? = nil
+    @Published public private(set) var isLoading: Bool = false
+    
+    public init(service: EmployeeService = EmployeeService()) {
+        self.service = service
+    }
+    
+    public func fetchEmployees() {
+        // resetting values out the values before fetching new data
+        errorMessage = nil
+        isLoading = true
+
+        Task {
+            do {
+                // Fetch employees using the async method
+                let wrapper = try await service.getEmployees(serviceMode)
+                
+                // Update published properties
+                self.employees = wrapper.employees
+                self.isLoading = false
+
+            } catch {
+                // Handle errors
+                self.employees = []
+                self.isLoading = false
+                self.errorMessage = "An unexpected error occurred, please try to refresh"
+            }
+        }
+
+    }
+    
+    public func changeMode(to mode: EmployeeServiceMode) {
+        serviceMode = mode
+        fetchEmployees()
+    }
+}
+

EmployeeDirectory/Views/EmployeeTableViewCell.swift

@@ -0,0 +1,93 @@
+//
+//  EmployeeTableViewCell.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+import UIKit
+import Combine
+
+public class EmployeeTableViewCell: UITableViewCell {
+    static let identifier = "EmployeeTableViewCell"
+    
+    private let photoImageView = UIImageView()
+    private let nameLabel = UILabel()
+    private let emailLabel = UILabel()
+    private let stackView = UIStackView()
+    
+    private var cancellable: AnyCancellable?
+
+    public override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
+        super.init(style: style, reuseIdentifier: reuseIdentifier)
+        setupUI()
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    private func setupUI() {
+        // Configure photoImageView
+        photoImageView.contentMode = .scaleAspectFill
+        photoImageView.clipsToBounds = true
+        photoImageView.layer.cornerRadius = 25
+        photoImageView.translatesAutoresizingMaskIntoConstraints = false
+        photoImageView.image = UIImage(systemName: "person.crop.circle")
+        
+        // Configure labels with text styles
+        nameLabel.font = UIFont.preferredFont(forTextStyle: .headline) // Bold, prominent text
+        nameLabel.adjustsFontForContentSizeCategory = true // Adapts to Dynamic Type
+        
+        emailLabel.font = UIFont.preferredFont(forTextStyle: .body)
+        emailLabel.textColor = .blue
+        emailLabel.adjustsFontForContentSizeCategory = true // Adapts to Dynamic Type
+        
+        // Configure stackView
+        stackView.axis = .vertical
+        stackView.spacing = 5
+        stackView.translatesAutoresizingMaskIntoConstraints = false
+        
+        // Add labels to stackView
+        stackView.addArrangedSubview(nameLabel)
+        stackView.addArrangedSubview(emailLabel)
+        
+        // Add subviews
+        contentView.addSubview(photoImageView)
+        contentView.addSubview(stackView)
+        
+        // Add constraints
+        NSLayoutConstraint.activate([
+            photoImageView.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10),
+            photoImageView.centerYAnchor.constraint(equalTo: contentView.centerYAnchor),
+            photoImageView.widthAnchor.constraint(equalToConstant: 50),
+            photoImageView.heightAnchor.constraint(equalToConstant: 50),
+            
+            stackView.leadingAnchor.constraint(equalTo: photoImageView.trailingAnchor, constant: 10),
+            stackView.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10),
+            stackView.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 10),
+            stackView.bottomAnchor.constraint(lessThanOrEqualTo: contentView.bottomAnchor, constant: -10)
+        ])
+    }
+    
+    public override func prepareForReuse() {
+        super.prepareForReuse()
+        photoImageView.image = UIImage(systemName: "person.crop.circle")
+        nameLabel.text = nil
+        emailLabel.text = nil
+    }
+    
+    public func configure(with viewModel: EmployeeCellViewModel) {
+
+        // Bind the image to the photoImageView
+        cancellable = viewModel.$smallPhoto
+            .receive(on: DispatchQueue.main)
+            .sink { [weak self] image in
+                self?.photoImageView.image = image
+            }
+
+        // Bind data to UI components
+        nameLabel.text = viewModel.fullName
+        emailLabel.text = viewModel.emailAddress
+        
+    }
+}

EmployeeDirectory/Views/TableFooterView.swift

@@ -0,0 +1,51 @@
+//
+//  EmptyStateFooterView.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+import UIKit
+
+public class TableFooterView: UIView {
+    
+    /// Label used to show the message
+    private let messageLabel: UILabel = {
+        let label = UILabel()
+        label.textColor = .gray
+        label.textAlignment = .center
+        label.font = UIFont.preferredFont(forTextStyle: .body) // Use a text style for Dynamic Type
+        label.adjustsFontForContentSizeCategory = true // Enable Dynamic Type adjustments
+        label.numberOfLines = 0
+        label.translatesAutoresizingMaskIntoConstraints = false
+        return label
+    }()
+    
+    init(message: String) {
+        super.init(frame: .zero)
+        setupUI()
+        update(message: message)
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    /// Setup the UI
+    private func setupUI() {
+        addSubview(messageLabel)
+        NSLayoutConstraint.activate([
+            messageLabel.centerXAnchor.constraint(equalTo: centerXAnchor),
+            messageLabel.centerYAnchor.constraint(equalTo: centerYAnchor),
+            messageLabel.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 16),
+            messageLabel.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -16)
+        ])
+    }
+    
+    
+    /// Updates the Current Message
+    /// - Parameter message: message to show
+    public func update(message: String) {
+        messageLabel.text = message
+    }
+    
+}

EmployeeDirectoryTests/EmployeeDirectoryTests.swift

@@ -6,12 +6,44 @@
 //
 
 import Testing
+import XCTest
+
 @testable import EmployeeDirectory
 
 struct EmployeeDirectoryTests {
-
-    @Test func example() async throws {
-        // Write your test here and use APIs like `#expect(...)` to check expected conditions.
+    
+    @Test func getEmployeesValid() async throws {
+        do {
+            let wrapper = try await EmployeeService().getEmployees(.production)
+            #expect(wrapper.employees.count == 11)
+        } catch {
+            XCTFail("Unexpected error: \(error)")
+        }
+    }
+    
+    @Test func getEmployeesMalformed() async throws {
+        do {
+            let wrapper = try await EmployeeService().getEmployees(.malformed)
+            XCTFail("Expected to throw, but got \(wrapper.employees.count) employees")
+        } catch let error as NetworkServiceError {
+            switch error {
+            case .invalidResponse:
+                XCTAssertTrue(true, "Correctly threw invalidResponse error")
+            default:
+                XCTFail("Expected NetworkServiceError.invalidResponse, but got \(error)")
+            }
+        } catch {
+            XCTFail("Unexpected error: \(error)")
+        }
+    }
+    
+    @Test func getEmployeesEmpty() async throws {
+        do {
+            let wrapper = try await EmployeeService().getEmployees(.empty)
+            #expect(wrapper.employees.count == 0)
+        } catch {
+            XCTFail("Unexpected error: \(error)")
+        }
     }
 
 }