Cache feed feature

.github/workflows/CI.yml

@@ -14,7 +14,7 @@ jobs:
     - uses: actions/checkout@v4
 
     - name: Select Xcode
-      run: sudo xcode-select -switch /Applications/Xcode_16.0.app
+      run: sudo xcode-select -switch /Applications/Xcode_16.2.app
 
     - name: Xcode version
       run: /usr/bin/xcodebuild -version

EssentialFeed/CI.xctestplan

@@ -0,0 +1,38 @@
+{
+  "configurations" : [
+    {
+      "id" : "FB6DC599-8749-4C8A-B598-7DA402070AD5",
+      "name" : "Test Scheme Action",
+      "options" : {
+
+      }
+    }
+  ],
+  "defaultOptions" : {
+    "testExecutionOrdering" : "random"
+  },
+  "testTargets" : [
+    {
+      "target" : {
+        "containerPath" : "container:EssentialFeed.xcodeproj",
+        "identifier" : "080EDEF921B6DA7E00813479",
+        "name" : "EssentialFeedTests"
+      }
+    },
+    {
+      "target" : {
+        "containerPath" : "container:EssentialFeed.xcodeproj",
+        "identifier" : "40B002442CF9E9DB0058D3E0",
+        "name" : "EssentialFeedAPIEndToEndTests"
+      }
+    },
+    {
+      "target" : {
+        "containerPath" : "container:EssentialFeed.xcodeproj",
+        "identifier" : "40412A492DA67465004677C4",
+        "name" : "EssentialFeedCacheIntegrationTests"
+      }
+    }
+  ],
+  "version" : 1
+}

EssentialFeed/EssentialFeed.xcodeproj/xcshareddata/xcschemes/CI.xcscheme

@@ -27,8 +27,13 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
-      shouldUseLaunchSchemeArgsEnv = "YES"
-      shouldAutocreateTestPlan = "YES">
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <TestPlans>
+         <TestPlanReference
+            reference = "container:CI.xctestplan"
+            default = "YES">
+         </TestPlanReference>
+      </TestPlans>
       <Testables>
          <TestableReference
             skipped = "NO">

EssentialFeed/EssentialFeed.xcodeproj/xcshareddata/xcschemes/EssentialFeedCacheIntegrationTests.xcscheme

@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "1620"
+   version = "1.7">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES"
+      buildArchitectures = "Automatic">
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <TestPlans>
+         <TestPlanReference
+            reference = "container:EssentialFeedCacheIntegrationTests.xctestplan"
+            default = "YES">
+         </TestPlanReference>
+      </TestPlans>
+      <Testables>
+         <TestableReference
+            skipped = "NO"
+            parallelizable = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "40412A492DA67465004677C4"
+               BuildableName = "EssentialFeedCacheIntegrationTests.xctest"
+               BlueprintName = "EssentialFeedCacheIntegrationTests"
+               ReferencedContainer = "container:EssentialFeed.xcodeproj">
+            </BuildableReference>
+         </TestableReference>
+      </Testables>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

EssentialFeed/EssentialFeed/Feed Cache/CoreDataStore.swift

@@ -0,0 +1,151 @@
+//
+//  CoreDataStore.swift
+//  EssentialFeed
+//
+//  Created by Cristian Felipe Patiño Rojas on 8/4/25.
+//
+
+import CoreData
+
+public final class CoreDataFeedStore: FeedStore {
+
+    let container: NSPersistentContainer
+    private let context: NSManagedObjectContext
+    public init(storeURL: URL, bundle: Bundle = .main) throws {
+        container = try NSPersistentContainer.load(
+            modelName: "FeedStore",
+            url: storeURL,
+            in: bundle
+        )
+        context = container.newBackgroundContext()
+    }
+
+    public func retrieve(completion: @escaping RetrievalCompletion) {
+        context.perform { [context] in
+
+            do {
+                if let cache = try ManagedCache.find(in: context) {
+                    completion(.found(feed: cache.localFeed, timestamp: cache.timestamp))
+                } else {
+                    completion(.empty)
+                }
+            } catch {
+                completion(.failure(error))
+            }
+        }
+    }
+
+    public func insert(_ feed: [LocalFeedImage], timestamp: Date, completion: @escaping InsertionCompletion) {
+        context.perform { [context] in
+            do {
+                let managedCache = try ManagedCache.newUniqueInstance(in: context)
+                managedCache.timestamp = timestamp
+                managedCache.feed = ManagedFeedImage.images(
+                    from: feed,
+                    in: context
+                )
+                try context.save()
+                completion(nil)
+            } catch {
+                completion(error)
+            }
+        }
+
+    }
+
+
+    public func deleteCachedFeed(completion: @escaping DeletionCompletion) {
+       completion(nil)
+    }
+}
+
+private extension NSPersistentContainer {
+    enum LoadingError: Error {
+        case modelNotFound
+        case failedToPersistentStores(Error)
+    }
+
+    static func load(
+        modelName name: String,
+        url: URL,
+        in bundle: Bundle
+    ) throws -> NSPersistentContainer {
+        guard let model = NSManagedObjectModel.with(name: name, in: bundle) else { throw LoadingError.modelNotFound }
+        let container = NSPersistentContainer(name: name, managedObjectModel: model)
+
+        container.persistentStoreDescriptions = [
+            NSPersistentStoreDescription(url: url)
+        ]
+
+        var loadError: Error?
+        container.loadPersistentStores {
+            loadError = $1
+        }
+
+        try loadError.map {
+            throw LoadingError.failedToPersistentStores($0)
+        }
+
+        return container
+    }
+}
+
+private extension NSManagedObjectModel {
+    static func with(name: String, in bundle: Bundle) -> NSManagedObjectModel? {
+        return bundle.url(forResource: name, withExtension: "momd")
+            .flatMap {
+                NSManagedObjectModel(contentsOf: $0)
+            }
+    }
+}
+
+@objc(ManagedCache)
+private class ManagedCache: NSManagedObject {
+    @NSManaged var timestamp: Date
+    @NSManaged var feed: NSOrderedSet
+
+    var localFeed: [LocalFeedImage] {
+        return feed.compactMap { ($0 as? ManagedFeedImage)?.local }
+    }
+
+    static func find(in context: NSManagedObjectContext) throws -> ManagedCache? {
+        let request = NSFetchRequest<ManagedCache>(entityName: entity().name!)
+        request.returnsObjectsAsFaults = false
+        return try context.fetch(request).first
+    }
+
+    static func newUniqueInstance(in context: NSManagedObjectContext) throws -> ManagedCache {
+        try find(in: context).map(context.delete)
+        return ManagedCache(context: context)
+    }
+}
+
+@objc(ManagedFeedImage)
+private class ManagedFeedImage: NSManagedObject {
+    @NSManaged var id: UUID
+    @NSManaged var imageDescription: String?
+    @NSManaged var location: String?
+    @NSManaged var url: URL
+    @NSManaged var cache: ManagedCache
+
+    static func images(from localFeed: [LocalFeedImage], in context: NSManagedObjectContext) -> NSOrderedSet {
+        let managedFeedImages = localFeed.map {
+            let managedFeedImage = ManagedFeedImage(context: context)
+            managedFeedImage.id = $0.id
+            managedFeedImage.imageDescription = $0.description
+            managedFeedImage.location = $0.location
+            managedFeedImage.url = $0.url
+            return managedFeedImage
+        }
+        return NSOrderedSet(array: managedFeedImages)
+    }
+
+    var local: LocalFeedImage {
+        LocalFeedImage(
+            id: id,
+            description: imageDescription,
+            location: location,
+            url: url
+        )
+    }
+}

EssentialFeed/EssentialFeed/Feed Cache/FeedCachePolicy.swift

@@ -0,0 +1,20 @@
+//
+//  FeedCachePolicy.swift
+//  EssentialFeed
+//
+//  Created by Cristian Felipe Patiño Rojas on 4/4/25.
+//
+
+import Foundation
+
+final class FeedCachePolicy {
+    private static let calendar = Calendar(identifier: .gregorian)
+    private static var maxCacheAgeInDays: Int { return 7 }
+    private init() {}
+    static func validate(_ timestamp: Date, against date: Date) -> Bool {
+        guard let maxCacheAge = calendar.date(byAdding: .day, value: maxCacheAgeInDays, to: timestamp) else {
+            return false
+        }
+        return date < maxCacheAge
+    }
+}

EssentialFeed/EssentialFeed/Feed Cache/FeedStore.swift

@@ -0,0 +1,36 @@
+//
+//  FeedStore.swift
+//  EssentialFeed
+//
+//  Created by Cristian Felipe Patiño Rojas on 3/4/25.
+//
+
+import Foundation
+
+
+public typealias CacheFeed = (feed: [LocalFeedImage], timestamp: Date)
+
+public protocol FeedStore {
+    typealias DeletionResult = Result<Void, Error>
+    typealias DeletionCompletion = (DeletionResult) -> Void
+
+    typealias InsertionResult = Result<Void, Error>
+    typealias InsertionCompletion = (InsertionResult) -> Void
+
+    typealias RetrievalResult = Result<CacheFeed?, Error>
+    typealias RetrievalCompletion = (RetrievalResult) -> Void
+
+    /// The completion handler can be invoked in any thread.
+    /// Clients are responsible to dispatch to appropiate threads, if needed.
+    func deleteCachedFeed(completion: @escaping DeletionCompletion)
+
+    /// The completion handler can be invoked in any thread.
+    /// Clients are responsible to dispatch to appropiate threads, if needed.
+    func insert(_ feed: [LocalFeedImage], timestamp: Date, completion: @escaping InsertionCompletion)
+
+    /// The completion handler can be invoked in any thread.
+    /// Clients are responsible to dispatch to appropiate threads, if needed.
+    func retrieve(completion: @escaping RetrievalCompletion)
+}
+
+