Image Comments API

EssentialApp/EssentialApp/CombineHelpers.swift

@@ -7,6 +7,22 @@ import Foundation
 import Combine
 import EssentialFeed
 
+public extension HTTPClient {
+    typealias Publisher = AnyPublisher<(Data, HTTPURLResponse), Error>
+
+    func getPublisher(url: URL) -> Publisher {
+        var task: HTTPClientTask?
+
+        return Deferred {
+            Future { completion in
+                task = self.get(from: url, completion: completion)
+            }
+        }
+        .handleEvents(receiveCancel: { task?.cancel() })
+        .eraseToAnyPublisher()
+    }
+}
+
 public extension FeedImageDataLoader {
     typealias Publisher = AnyPublisher<Data, Error>
 
@@ -37,7 +53,7 @@ private extension FeedImageDataCache {
     }
 }
 
-public extension FeedLoader {
+public extension LocalFeedLoader {
     typealias Publisher = AnyPublisher<[FeedImage], Error>
 
     func loadPublisher() -> Publisher {

EssentialApp/EssentialApp/FeedLoaderPresentationAdapter.swift

@@ -8,11 +8,11 @@ import EssentialFeed
 import EssentialFeediOS
 
 final class FeedLoaderPresentationAdapter: FeedViewControllerDelegate {
-    private let feedLoader: () -> FeedLoader.Publisher
+    private let feedLoader: () -> AnyPublisher<[FeedImage], Error>
     private var cancellable: Cancellable?
     var presenter: FeedPresenter?
 
-    init(feedLoader: @escaping () -> FeedLoader.Publisher) {
+    init(feedLoader: @escaping () -> AnyPublisher<[FeedImage], Error>) {
         self.feedLoader = feedLoader
     }
 

EssentialApp/EssentialApp/FeedUIComposer.swift

@@ -12,7 +12,7 @@ public final class FeedUIComposer {
     private init() {}
 
     public static func feedComposedWith(
-        feedLoader: @escaping () -> FeedLoader.Publisher,
+        feedLoader: @escaping () -> AnyPublisher<[FeedImage], Error>,
         imageLoader: @escaping (URL) -> FeedImageDataLoader.Publisher
     ) -> FeedViewController {
         let presentationAdapter = FeedLoaderPresentationAdapter(feedLoader: feedLoader)

EssentialApp/EssentialApp/SceneDelegate.swift

@@ -26,9 +26,7 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         LocalFeedLoader(store: store, currentDate: Date.init)
     }()
 
-    private let url = URL(string: "https://ile-api.essentialdeveloper.com/essential-feed/v1/feed")!
-
-    private lazy var remoteFeedLoader = RemoteFeedLoader(url: url, client: httpClient)
+    private let remoteURL = URL(string: "https://ile-api.essentialdeveloper.com/essential-feed/v1/feed")!
 
     convenience init(httpClient: HTTPClient, store: FeedStore & FeedImageDataStore) {
         self.init()
@@ -56,22 +54,23 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         localFeedLoader.validateCache { _ in }
     }
 
-    private func makeRemoteFeedLoaderWithLocalFallback() -> FeedLoader.Publisher {
-        return remoteFeedLoader
-            .loadPublisher()
+    private func makeRemoteFeedLoaderWithLocalFallback() -> AnyPublisher<[FeedImage], Error> {
+        return httpClient
+            .getPublisher(url: remoteURL)
+            .tryMap(FeedItemsMapper.map)
             .caching(to: localFeedLoader)
             .fallback(to: localFeedLoader.loadPublisher)
     }
 
     private func makeLocalImageLoaderWithRemoteFallback(url: URL) -> FeedImageDataLoader.Publisher {
-        let remoteImageLoader = RemoteFeedImageDataLoader(client: httpClient)
         let localImageLoader = LocalFeedImageDataLoader(store: store)
 
         return localImageLoader
             .loadImageDataPublisher(from: url)
-            .fallback(to: {
-                remoteImageLoader
-                    .loadImageDataPublisher(from: url)
+            .fallback(to: { [httpClient] in
+                httpClient
+                    .getPublisher(url: url)
+                    .tryMap(FeedImageDataMapper.map)
                     .caching(to: localImageLoader, using: url)
             })
     }

EssentialApp/EssentialAppTests/Helpers/FeedUIIntegrationTests+LoaderSpy.swift

@@ -6,30 +6,33 @@
 import Foundation
 import EssentialFeed
 import EssentialFeediOS
+import Combine
 
 extension FeedUIIntegrationTests {
 
-    class LoaderSpy: FeedLoader, FeedImageDataLoader {
+    class LoaderSpy: FeedImageDataLoader {
 
         // MARK: - FeedLoader
 
-        private var feedRequests = [(FeedLoader.Result) -> Void]()
+        private var feedRequests = [PassthroughSubject<[FeedImage], Error>]()
 
         var loadFeedCallCount: Int {
             return feedRequests.count
         }
 
-        func load(completion: @escaping (FeedLoader.Result) -> Void) {
-            feedRequests.append(completion)
+        func loadPublisher() -> AnyPublisher<[FeedImage], Error> {
+            let publisher = PassthroughSubject<[FeedImage], Error>()
+            feedRequests.append(publisher)
+            return publisher.eraseToAnyPublisher()
         }
 
         func completeFeedLoading(with feed: [FeedImage] = [], at index: Int = 0) {
-            feedRequests[index](.success(feed))
+            feedRequests[index].send(feed)
         }
 
         func completeFeedLoadingWithError(at index: Int = 0) {
             let error = NSError(domain: "an error", code: 404)
-            feedRequests[index](.failure(error))
+            feedRequests[index].send(completion: .failure(error))
         }
 
         // MARK: - FeedImageDataLoader