Implemented the showing of FeedUnavailableView views for the FeedListViewController view controller in the Feed framework.

Frameworks/Feed/Bundle/Resources/Catalogs/Localizable.xcstrings

@@ -120,6 +120,66 @@
           }
         }
       }
+    },
+    "view.feed-list.unavailable.empty.description.text" : {
+      "comment" : "The text for the description of the Unavailable component in the Feed List view when no items are available",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "No reviews matching the criteria have been found.\nPlease try fetching them at a later time."
+          }
+        }
+      }
+    },
+    "view.feed-list.unavailable.empty.title.text" : {
+      "comment" : "The text for the title of the Unavailable component in the Feed List view when no items are available",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "No reviews available"
+          }
+        }
+      }
+    },
+    "view.feed-list.unavailable.error.button.try-again.text" : {
+      "comment" : "The text for the Try Again button of the Unavailable component in the Feed List view when an error occurred",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Try fetching data again"
+          }
+        }
+      }
+    },
+    "view.feed-list.unavailable.error.description.text" : {
+      "comment" : "The text for the title of the Unavailable component in the Feed List view when an error occurred",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "An error occurred while trying to fetch the reviews.\nPlease try this operation them at a later time."
+          }
+        }
+      }
+    },
+    "view.feed-list.unavailable.error.title.text" : {
+      "comment" : "The text for the title of the Unavailable component in the Feed List view when an error occurred",
+      "extractionState" : "manual",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Something went wrong"
+          }
+        }
+      }
     }
   },
   "version" : "1.0"

Frameworks/Feed/Bundle/Sources/UI/View Controllers/FeedListViewController.swift

@@ -13,12 +13,14 @@ import ReviewsUIKit
 import SwiftUI
 import UIKit
 
-final class FeedListViewController: UITableViewController {
+final class FeedListViewController: UIViewController {
-
+    
     // MARK: Constants
     private let viewModel: ViewModel
     
     // MARK: Properties
+    private var unavailableView: FeedUnavailableView?
+    
     private var cancellables: Set<AnyCancellable> = []
     
     // MARK: Outlets
@@ -26,10 +28,10 @@ final class FeedListViewController: UITableViewController {
         let indicator = UIActivityIndicatorView()
         
         indicator.translatesAutoresizingMaskIntoConstraints = false
-
+        
         return indicator
     }()
-
+    
     private lazy var filterButton = {
         UIBarButtonItem(
             title: NSLocalizedString(
@@ -46,29 +48,27 @@ final class FeedListViewController: UITableViewController {
                     comment: .empty
                 ),
                 image: UIImage.Icon.star,
-                children: {
+                children: FilterOption.allCases.map { option -> UIAction in
-                    FilterOption.allCases.map { option -> UIAction in
                         .init(
                             title: option.text,
                             image: .init(systemName: option.icon)
                         ) { [weak self] _ in
                             self?.viewModel.filter(by: option)
                         }
-                    }
+                }
-                }()
             )
         )
     }()
     
     private lazy var pullControl = {
         let control = UIRefreshControl()
-
+        
         control.attributedTitle = .init(string: NSLocalizedString(
             .Key.PullToRefresh.title,
             bundle: .module,
             comment: .empty
         ))
-
+        
         control.addTarget(
             self,
             action: #selector(refresh(_:)),
@@ -77,12 +77,26 @@ final class FeedListViewController: UITableViewController {
         
         return control
     }()
+    
+    private lazy var tableView = {
+        let table = UITableView(
+            frame: .zero,
+            style: .plain
+        )
 
+        table.translatesAutoresizingMaskIntoConstraints = false
+
+        return table
+    }()
+    
     // MARK: Initialisers
     init(_ viewModel: ViewModel) {
         self.viewModel = viewModel
-
+        
-        super.init(style: .plain)
+        super.init(
+            nibName: nil,
+            bundle: nil
+        )
     }
     
     required init?(coder: NSCoder) {
@@ -93,11 +107,11 @@ final class FeedListViewController: UITableViewController {
     var items: [Review] {
         viewModel.items
     }
-
+    
     // MARK: UIViewController
     override func viewDidLoad() {
         super.viewDidLoad()
-
+        
         setNavigationBar()
         setView()
         setLayout()
@@ -107,15 +121,20 @@ final class FeedListViewController: UITableViewController {
         viewModel.fetch()
     }
     
-    // MARK: UITableViewDataSource
+}
-    override func tableView(
+
+// MARK: - UITableViewDataSource
+extension FeedListViewController: UITableViewDataSource {
+    
+    // MARK: Functions
+    func tableView(
         _ tableView: UITableView,
         numberOfRowsInSection section: Int
     ) -> Int {
         viewModel.itemsCount
     }
     
-    override func tableView(
+    func tableView(
         _ tableView: UITableView,
         cellForRowAt indexPath: IndexPath
     ) -> UITableViewCell {
@@ -126,8 +145,13 @@ final class FeedListViewController: UITableViewController {
         }
     }
     
-    // MARK: UITableViewDelegate
+}
-    override func tableView(
+
+// MARK: - UITableViewDelegate
+extension FeedListViewController: UITableViewDelegate {
+
+    // MARK: Functions
+    func tableView(
         _ tableView: UITableView,
         didSelectRowAt indexPath: IndexPath
     ) {
@@ -183,13 +207,78 @@ private extension FeedListViewController {
                 self?.activityIndicator.stopAnimating()
                 self?.pullControl.endRefreshing()
                 self?.tableView.reloadData()
-                self?.tableView.scrollToRow(
+
-                    at: .init(row: 0, section: 0),
+                if self?.viewModel.state == .populated {
-                    at: .middle,
+                    self?.tableView.scrollToRow(
-                    animated: true
+                        at: .init(row: 0, section: 0),
-                )
+                        at: .middle,
+                        animated: true
+                    )
+                }
             }
             .store(in: &cancellables)
+        
+        viewModel.$state
+            .dropFirst()
+            .receive(on: RunLoop.main)
+            .sink { [weak self] state in
+                switch state {
+                case .empty,
+                     .error:
+                    self?.insertUnavailableView(state)
+                default:
+                    self?.removeUnavailableView()
+                }
+                
+            }
+            .store(in: &cancellables)
+    }
+    
+    func insertUnavailableView(_ state: FeedListState) {
+        guard unavailableView == nil else { return }
+        
+        let isErrorState = state == .error
+        let unavailable = FeedUnavailableView(
+            systemImage: isErrorState
+                ? .Icon.error
+                : .Icon.empty,
+            title: NSLocalizedString(
+                isErrorState
+                    ? .Key.Unavailable.Title.error
+                    : .Key.Unavailable.Title.empty,
+                bundle: .module,
+                comment: .empty
+            ),
+            description: NSLocalizedString(
+                isErrorState
+                    ? .Key.Unavailable.Description.error
+                    : .Key.Unavailable.Description.empty,
+                bundle: .module,
+                comment: .empty
+            ),
+            button: isErrorState
+                ? NSLocalizedString(
+                    .Key.Unavailable.Button.tryAgain,
+                    bundle: .module,
+                    comment: .empty
+                )
+                : nil,
+            action: isErrorState
+                ? { self.viewModel.fetch() }
+                : nil
+        )
+        
+        addChild(unavailable)
+
+        view.addSubview(unavailable.view)
+        view.bringSubviewToFront(unavailable.view)
+        
+        // TODO: fix [this issue](https://stackoverflow.com/questions/70032739/why-does-swiftui-uihostingcontroller-have-extra-spacing) so autolayout can be used instead.
+        unavailable.view.frame = tableView.bounds
+
+        unavailable.didMove(toParent: self)
+
+        unavailableView = unavailable
     }
     
     func makeFeedItemCell(
@@ -245,10 +334,22 @@ private extension FeedListViewController {
         TopWordsCell.register(in: tableView)
     }
     
+    func removeUnavailableView() {
+        guard let unavailableView else { return }
+        
+        unavailableView.view.removeFromSuperview()
+
+        self.unavailableView = nil
+    }
+
     func setLayout() {
         NSLayoutConstraint.activate([
             activityIndicator.centerXAnchor.constraint(equalTo: view.centerXAnchor),
             activityIndicator.centerYAnchor.constraint(equalTo: view.safeAreaLayoutGuide.centerYAnchor),
+            tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+            tableView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            tableView.topAnchor.constraint(equalTo: view.topAnchor),
+            tableView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
         ])
     }
     
@@ -265,11 +366,14 @@ private extension FeedListViewController {
     }
     
     func setView() {
-        tableView.refreshControl = pullControl
+        view.addSubview(tableView)
-        
         view.addSubview(activityIndicator)
         view.bringSubviewToFront(activityIndicator)
         
+        tableView.delegate = self
+        tableView.refreshControl = pullControl
+        tableView.dataSource = self
+
         activityIndicator.startAnimating()
     }
     
@@ -309,6 +413,22 @@ private extension String {
         enum PullToRefresh {
             static let title = "view.feed-list.pull-to-refresh.title.text"
         }
+        
+        enum Unavailable {
+            enum Button {
+                static let tryAgain = "view.feed-list.unavailable.error.button.try-again.text"
+            }
+            
+            enum Description {
+                static let empty = "view.feed-list.unavailable.empty.description.text"
+                static let error = "view.feed-list.unavailable.empty.description.text"
+            }
+            
+            enum Title {
+                static let empty = "view.feed-list.unavailable.empty.title.text"
+                static let error = "view.feed-list.unavailable.error.title.text"
+            }
+        }
     }
 }
 
@@ -333,7 +453,7 @@ import ReviewsiTunesKit
 
 @available(iOS 17.0, *)
 #Preview("Feed List loading reviews") {
-    MockURLProtocol.response = .init(statusCode: 200)
+    MockURLProtocol.response = .init(statusCode: 404)
     
     return UINavigationController(rootViewController: FeedListViewController(.init(
         configuration: .init(session: .mock)

Libraries/UI/Kit/Sources/Extensions/String+Icons.swift

@@ -10,6 +10,8 @@ public extension String {
     enum Icon {
         
         // MARK: Constants
+        public static let empty = "list.star"
+        public static let error = "exclamationmark.triangle.fill"
         public static let info = "info.circle.fill"
         public static let person = "person.crop.circle.fill"
         public static let starAll = "a.circle"