now using diffable datasource

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/ViewControllers/EmployeesViewController.swift

@@ -34,24 +34,45 @@ class EmployeesViewController: UIViewController {
     // Prevents multiple calls during rapid scrolling
     private var isFetchingNextPage: Bool = false
 
+    private var dataSource: UITableViewDiffableDataSource<Int, Employee>!
+
     // MARK: - Public Methods
 
     public override func viewDidLoad() {
         super.viewDidLoad()
         setupUI()
+        setupDataSource()
         bindViewModel()
         viewModel.fetchEmployees()
     }
     
     // MARK: - Private Methods
-        
+    
+    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
+        }
+    }
+    
+    // MARK: - 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
         tableView.delegate = self
         view.addSubview(tableView)
         tableView.frame = view.bounds
@@ -108,13 +129,9 @@ class EmployeesViewController: UIViewController {
     /// Using the ViewModel setup combine handlers
     private func bindViewModel() {
         viewModel.$employees
-            .scan(([], [])) { previous, current in
-                (previous.1, current) // (oldValue, newValue)
-            }
             .receive(on: RunLoop.main)
-            .sink { [weak self] oldValue, newValue in
+            .sink { [weak self] employees in
-                self?.animateEmployeeChanges(from: oldValue, to: newValue)
+                self?.applySnapshot(employees: employees)
-                self?.updateFooter()
             }
             .store(in: &cancellables)
         
@@ -235,19 +252,3 @@ extension EmployeesViewController {
         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
-    }
-}