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/Logic/Enumerations/FeedListState.swift

@@ -0,0 +1,14 @@
+//
+//  FeedListState.swift
+//  ReviewsFeed
+//
+//  Created by Javier Cicchelli on 22/03/2024.
+//  Copyright © 2024 Röck+Cöde. All rights reserved.
+//
+
+enum FeedListState {
+    case empty
+    case error
+    case initial
+    case populated
+}

Frameworks/Feed/Bundle/Sources/Logic/View Models/FeedListViewModel.swift

@@ -24,6 +24,7 @@ extension FeedListViewController {
         @Published var isFilterEnabled: Bool = false
         @Published var isFiltering: Bool = false
         @Published var isLoading: Bool = false
+        @Published var state: FeedListState = .initial
 
         var items: [Review] = []
         var words: [TopWord] = []
@@ -88,11 +89,14 @@ extension FeedListViewController {
                     items = filter == .all
                         ? reviewsAll
                         : reviewsFiltered[filter] ?? []
-                    
+
                     isFilterEnabled = !items.isEmpty
+                    state = items.isEmpty
+                        ? .empty
+                        : .populated
                 } catch {
-                    // TODO: handle this error gracefully.
+                    items = []
-                    print("ERROR: \(error.localizedDescription)")
+                    state = .error
                 }
 
                 isLoading = false
@@ -111,7 +115,12 @@ extension FeedListViewController {
         }
         
         func item(for index: Int) -> Review? {
-            guard index < items.count else { return nil }
+            guard
+                !items.isEmpty,
+                index < items.count
+            else {
+                return nil
+            }
             
             return isWordsShowing
                 ? items[index - 1]

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"
+            }
+        }
     }
 }
 
@@ -331,15 +451,6 @@ private extension UIEdgeInsets {
 #if DEBUG
 import ReviewsiTunesKit
 
-@available(iOS 17.0, *)
-#Preview("Feed List loading reviews") {
-    MockURLProtocol.response = .init(statusCode: 200)
-    
-    return UINavigationController(rootViewController: FeedListViewController(.init(
-        configuration: .init(session: .mock)
-    )))
-}
-
 @available(iOS 17.0, *)
 #Preview("Feed List with few reviews") {
     MockURLProtocol.response = .init(
@@ -410,6 +521,15 @@ import ReviewsiTunesKit
     )))
 }
 
+@available(iOS 17.0, *)
+#Preview("Feed List with error when loading reviews") {
+    MockURLProtocol.response = .init(statusCode: 404)
+    
+    return UINavigationController(rootViewController: FeedListViewController(.init(
+        configuration: .init(session: .mock)
+    )))
+}
+
 @available(iOS 17.0, *)
 #Preview("Feed List with live reviews") {
     return UINavigationController(rootViewController: FeedListViewController(.init()))

Frameworks/Feed/Bundle/Sources/UI/Views/FeedUnavailableView.swift

@@ -0,0 +1,47 @@
+//
+//  FeedUnavailableView.swift
+//  Feed
+//
+//  Created by Javier Cicchelli on 22/03/2024.
+//  Copyright © 2024 Röck+Cöde. All rights reserved.
+//
+
+import ReviewsUIKit
+import SwiftUI
+import UIKit
+
+
+final class FeedUnavailableView: UIHostingController<UnavailableView> {
+    
+    // MARK: Initialisers
+    convenience init(
+        systemImage: String,
+        title: String,
+        description: String,
+        button: String? = nil,
+        action: (() -> Void)? = nil
+    ) {
+        self.init(rootView: .init(
+            systemImage: systemImage,
+            title: title,
+            description: description,
+            button: button,
+            action: action
+        ))
+    }
+    
+    // MARK: Functions
+    override func viewSafeAreaInsetsDidChange() {
+        super.viewSafeAreaInsetsDidChange()
+        
+        if view.safeAreaInsets.bottom > 0 {
+            additionalSafeAreaInsets = .init(
+                top: 0,
+                left: 0,
+                bottom: -view.safeAreaInsets.bottom,
+                right: 0
+            )
+        }
+    }
+    
+}

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"

Libraries/UI/Kit/Sources/Views/UnavailableView.swift

@@ -0,0 +1,105 @@
+//
+//  UnavailableView.swift
+//  ReviewsUIKit
+//
+//  Created by Javier Cicchelli on 22/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import SwiftUI
+
+public struct UnavailableView: View {
+    
+    // MARK: Constants
+    private let description: String
+    private let systemImage: String
+    private let title: String
+
+    private let action: (() -> Void)?
+    private let button: String?
+
+    // MARK: Initialisers
+    public init(
+        systemImage: String,
+        title: String,
+        description: String,
+        button: String? = nil,
+        action: (() -> Void)? = nil
+    ) {
+        self.action = action
+        self.button = button
+        self.description = description
+        self.systemImage = systemImage
+        self.title = title
+    }
+
+    // MARK: Body
+    public var body: some View {
+        if #available(iOS 17.0, *) {
+            if let button, let action {
+                ContentUnavailableView {
+                    Label(title, systemImage: systemImage)
+                } description: {
+                    Text(description)
+                } actions: {
+                    Button(action: action) {
+                        Text(button)
+                    }
+                }
+            } else {
+                ContentUnavailableView(
+                    title,
+                    systemImage: systemImage,
+                    description: Text(description)
+                )
+            }
+        } else {
+            VStack(spacing: 24) {
+                Image(systemName: systemImage)
+                    .resizable()
+                    .frame(width: 52, height: 52)
+                    .foregroundColor(.secondary)
+
+                VStack {
+                    Text(title)
+                        .font(.title2.bold())
+                        .foregroundColor(.primary)
+                    
+                    Text(description)
+                        .font(.subheadline)
+                        .foregroundColor(.secondary)
+                }
+                .multilineTextAlignment(.center)
+                
+                if let button, let action {
+                    Button(action: action) {
+                        Text(button)
+                            .font(.subheadline)
+                    }
+                }
+            }
+            .padding(.horizontal, 52)
+        }
+    }
+    
+}
+
+// MARK: - Previews
+#Preview("Unavailable View with image, title, and description") {
+    UnavailableView(
+        systemImage: "star",
+        title: "Some title goes here...",
+        description: "Some long, explanatory description goes in here..."
+    )
+}
+
+#Preview("Unavailable View with image, title, description, button, and action") {
+    UnavailableView(
+        systemImage: "star",
+        title: "Some title goes here...",
+        description: "Some long, explanatory description goes in here...",
+        button: "Some button text here..."
+    ) {
+        // On action closure.
+    }
+}

Reviews.xcodeproj/project.pbxproj

@@ -13,6 +13,8 @@
 		028134712BACC8CC0074AB4B /* FeedListConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = 028134702BACC8CC0074AB4B /* FeedListConfiguration.swift */; };
 		028134822BACCC780074AB4B /* FeedListCoordination.swift in Sources */ = {isa = PBXBuildFile; fileRef = 028134812BACCC770074AB4B /* FeedListCoordination.swift */; };
 		028134842BACD0B20074AB4B /* FeedItemCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 028134832BACD0B20074AB4B /* FeedItemCoordinator.swift */; };
+		028134882BAD01A60074AB4B /* FeedListState.swift in Sources */ = {isa = PBXBuildFile; fileRef = 028134872BAD01A60074AB4B /* FeedListState.swift */; };
+		0281348A2BAD08AB0074AB4B /* FeedUnavailableView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 028134892BAD08AB0074AB4B /* FeedUnavailableView.swift */; };
 		02909E792BAB6B0200710E14 /* FilterOption.swift in Sources */ = {isa = PBXBuildFile; fileRef = 02909E782BAB6B0200710E14 /* FilterOption.swift */; };
 		02909E7B2BAB6D2E00710E14 /* Bundle+Constants.swift in Sources */ = {isa = PBXBuildFile; fileRef = 02909E7A2BAB6D2E00710E14 /* Bundle+Constants.swift */; };
 		02909E7D2BAB7FFE00710E14 /* Review+DTOs.swift in Sources */ = {isa = PBXBuildFile; fileRef = 02909E7C2BAB7FFE00710E14 /* Review+DTOs.swift */; };
@@ -68,6 +70,8 @@
 		028134702BACC8CC0074AB4B /* FeedListConfiguration.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FeedListConfiguration.swift; sourceTree = "<group>"; };
 		028134812BACCC770074AB4B /* FeedListCoordination.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FeedListCoordination.swift; sourceTree = "<group>"; };
 		028134832BACD0B20074AB4B /* FeedItemCoordinator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FeedItemCoordinator.swift; sourceTree = "<group>"; };
+		028134872BAD01A60074AB4B /* FeedListState.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FeedListState.swift; sourceTree = "<group>"; };
+		028134892BAD08AB0074AB4B /* FeedUnavailableView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FeedUnavailableView.swift; sourceTree = "<group>"; };
 		02909E782BAB6B0200710E14 /* FilterOption.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FilterOption.swift; sourceTree = "<group>"; };
 		02909E7A2BAB6D2E00710E14 /* Bundle+Constants.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Bundle+Constants.swift"; sourceTree = "<group>"; };
 		02909E7C2BAB7FFE00710E14 /* Review+DTOs.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Review+DTOs.swift"; sourceTree = "<group>"; };
@@ -168,6 +172,7 @@
 			children = (
 				0220ADA22BA90646001E6A9F /* FeedItemView.swift */,
 				02EACF312BABB23A00FF8ECD /* TopWordsView.swift */,
+				028134892BAD08AB0074AB4B /* FeedUnavailableView.swift */,
 			);
 			path = Views;
 			sourceTree = "<group>";
@@ -200,6 +205,7 @@
 		02909E772BAB6AD500710E14 /* Enumerations */ = {
 			isa = PBXGroup;
 			children = (
+				028134872BAD01A60074AB4B /* FeedListState.swift */,
 				02909E782BAB6B0200710E14 /* FilterOption.swift */,
 			);
 			path = Enumerations;
@@ -498,6 +504,7 @@
 				02DC7FAC2BA51B4C000EEEBE /* FeedItemViewController.swift in Sources */,
 				02909E7B2BAB6D2E00710E14 /* Bundle+Constants.swift in Sources */,
 				02EACF2E2BABA34600FF8ECD /* FeedItemCell.swift in Sources */,
+				0281348A2BAD08AB0074AB4B /* FeedUnavailableView.swift in Sources */,
 				028134842BACD0B20074AB4B /* FeedItemCoordinator.swift in Sources */,
 				02909E7D2BAB7FFE00710E14 /* Review+DTOs.swift in Sources */,
 				0220ADA32BA90646001E6A9F /* FeedItemView.swift in Sources */,
@@ -508,6 +515,7 @@
 				02EACF322BABB23A00FF8ECD /* TopWordsView.swift in Sources */,
 				028134712BACC8CC0074AB4B /* FeedListConfiguration.swift in Sources */,
 				028134822BACCC780074AB4B /* FeedListCoordination.swift in Sources */,
+				028134882BAD01A60074AB4B /* FeedListState.swift in Sources */,
 				02909E792BAB6B0200710E14 /* FilterOption.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;