[GWL-405] 무한스크롤 기능 구현 (#439)

* feat: HomeFeature DownSampling 모듈 추가

* feat: 다운 샘플링 적용

* feat: ImageCacher 및 PrepareForReuse 적용

* feat: Repository And UseCase 파일 생성

* feat: FetchCheckManager 구현

* move: 파일 위치 변경

* feat: coordaintor 및 UseCase 적용

* feat: 무한 스크롤 구현

* delete: 목 데이터 삭제

* feat: 화면에 피드가 표시되었을 때 Page넘버를 증가하는 기능 추가

* delete: Home화면 Resources 폴더 제거

* style: 피드백 적용 및 쓰지 않는 import문 제거

iOS/Projects/App/WeTri/Sources/CommonScene/Coordinator/AppCoordinator.swift

@@ -29,7 +29,7 @@ final class AppCoordinator: AppCoordinating {
   }
 
   func start() {
-    showSplashFlow()
+    showTabBarFlow()
   }
 
   private func showSplashFlow() {

iOS/Projects/App/WeTri/Sources/TabBarScene/Coordinator/TabBarCoordinator.swift

@@ -40,7 +40,7 @@ final class TabBarCoordinator: TabBarCoordinating {
   }
 
   func start() {
-    let tabBarViewControllers = [TabBarPage.record, TabBarPage.profile].map {
+    let tabBarViewControllers = TabBarPage.allCases.map {
       return makePageNavigationController(page: $0)
     }
     let tabBarController = makeTabBarController(tabBarViewControllers: tabBarViewControllers)
@@ -58,6 +58,13 @@ final class TabBarCoordinator: TabBarCoordinating {
 
   private func startTabBarCoordinator(page: TabBarPage, pageNavigationViewController: UINavigationController) {
     switch page {
+    case .home:
+      let coordinator = HomeCoordinator(
+        navigationController: pageNavigationViewController,
+        delegate: self
+      )
+      childCoordinators.append(coordinator)
+      coordinator.start()
     case .record:
       let recordCoordinator = RecordFeatureCoordinator(
         navigationController: pageNavigationViewController,

iOS/Projects/Features/Home/Project.swift

@@ -7,7 +7,16 @@ let project = Project.makeModule(
   targets: .feature(
     .home,
     testingOptions: [.unitTest],
-    dependencies: [.designSystem, .log, .combineCocoa, .trinet, .combineExtension, .coordinator, .commonNetworkingKeyManager],
+    dependencies: [
+      .designSystem,
+      .log,
+      .combineCocoa,
+      .trinet,
+      .combineExtension,
+      .coordinator,
+      .commonNetworkingKeyManager,
+      .downSampling,
+    ],
     testDependencies: []
   )
 )

iOS/Projects/Features/Home/Sources/Data/FeedRepository.swift

@@ -0,0 +1,66 @@
+//
+//  FeedRepository.swift
+//  HomeFeature
+//
+//  Created by MaraMincho on 12/7/23.
+//  Copyright © 2023 kr.codesquad.boostcamp8. All rights reserved.
+//
+
+import Combine
+import CommonNetworkingKeyManager
+import Foundation
+import Trinet
+
+// MARK: - FeedRepository
+
+public struct FeedRepository: FeedRepositoryRepresentable {
+  let decoder = JSONDecoder()
+  let provider: TNProvider<FeedEndPoint>
+  init(session: URLSessionProtocol = URLSession.shared) {
+    provider = .init(session: session)
+  }
+
+  public func fetchFeed(at page: Int) -> AnyPublisher<[FeedElement], Never> {
+    return Future<[FeedElement], Error> { promise in
+      Task { [provider] in
+        do {
+          let data = try await provider.request(.fetchPosts(page: page), interceptor: TNKeychainInterceptor.shared)
+          let feedElementList = try decoder.decode([FeedElement].self, from: data)
+          promise(.success(feedElementList))
+        } catch {
+          promise(.failure(error))
+        }
+      }
+    }
+    .catch { _ in return Empty() }
+    .eraseToAnyPublisher()
+  }
+}
+
+// MARK: - FeedEndPoint
+
+public enum FeedEndPoint: TNEndPoint {
+  case fetchPosts(page: Int)
+  public var path: String {
+    return ""
+  }
+
+  public var method: TNMethod {
+    return .post
+  }
+
+  public var query: Encodable? {
+    return nil
+  }
+
+  public var body: Encodable? {
+    switch self {
+    case let .fetchPosts(page):
+      return page
+    }
+  }
+
+  public var headers: TNHeaders {
+    return .default
+  }
+}

iOS/Projects/Features/Home/Sources/Domain/Entity/FeedElement.swift

@@ -8,7 +8,7 @@
 
 import Foundation
 
-struct FeedElement: Hashable {
+public struct FeedElement: Hashable, Codable {
   /// 개시물의 아이디 입니다.
   let ID: Int
 

iOS/Projects/Features/Home/Sources/Domain/HomeUseCase.swift

@@ -6,4 +6,64 @@
 //  Copyright © 2023 kr.codesquad.boostcamp8. All rights reserved.
 //
 
+import Combine
 import Foundation
+
+// MARK: - HomeUseCaseRepresentable
+
+public protocol HomeUseCaseRepresentable {
+  func fetchFeed() -> AnyPublisher<[FeedElement], Never>
+  mutating func didDisplayFeed()
+}
+
+// MARK: - HomeUseCase
+
+public struct HomeUseCase: HomeUseCaseRepresentable {
+  private let feedRepositoryRepresentable: FeedRepositoryRepresentable
+
+  private var latestFeedPage = 0
+  private var feedElementPublisher: PassthroughSubject<[FeedElement], Never> = .init()
+  private let checkManager: FetchCheckManager = .init()
+
+  public init(feedRepositoryRepresentable: FeedRepositoryRepresentable) {
+    self.feedRepositoryRepresentable = feedRepositoryRepresentable
+  }
+
+  public func fetchFeed() -> AnyPublisher<[FeedElement], Never> {
+    if checkManager[latestFeedPage] == false {
+      return Empty().eraseToAnyPublisher()
+    }
+    checkManager[latestFeedPage] = true
+    return feedElementPublisher.eraseToAnyPublisher()
+  }
+
+  public mutating func didDisplayFeed() {
+    latestFeedPage += 1
+  }
+}
+
+// MARK: - FetchCheckManager
+
+final class FetchCheckManager {
+  subscript(page: Int) -> Bool {
+    get {
+      return check(at: page)
+    }
+    set {
+      set(at: page)
+    }
+  }
+
+  private var requestedFetchPageNumber: [Int: Bool] = [:]
+  /// FetchCheckManager를 통해서 특정 페이지에 대해 요청을 했다고 저장합니다.
+  private func set(at page: Int) {
+    requestedFetchPageNumber[page] = true
+  }
+
+  /// FetchCheckManager를 통해서, 특정 페이지에 대한 과거 요청에 대해서 살펴 봅니다.
+  ///
+  /// 만약 요청한 적이 없다면 false를, 요청을 했다면 true를 리턴
+  private func check(at page: Int) -> Bool {
+    return requestedFetchPageNumber[page] ?? false
+  }
+}

iOS/Projects/Features/Home/Sources/Domain/RepositoryInterface/FeedRepositoryRepresentable.swift

@@ -0,0 +1,16 @@
+//
+//  FeedRepositoryRepresentable.swift
+//  HomeFeature
+//
+//  Created by MaraMincho on 1/2/24.
+//  Copyright © 2024 kr.codesquad.boostcamp8. All rights reserved.
+//
+
+import Combine
+import Foundation
+
+// MARK: - FeedRepositoryRepresentable
+
+public protocol FeedRepositoryRepresentable {
+  func fetchFeed(at page: Int) -> AnyPublisher<[FeedElement], Never>
+}

iOS/Projects/Features/Home/Sources/Coordinator/HomeCoordinator.swift → iOS/Projects/Features/Home/Sources/Presntaion/Coordinator/HomeCoordinator.swift

@@ -37,7 +37,11 @@ public final class HomeCoordinator: HomeCoordinating {
   }
 
   public func pushHome() {
-    let viewModel = HomeViewModel()
+    let repository = FeedRepository(session: URLSession.shared)
+
+    let useCase = HomeUseCase(feedRepositoryRepresentable: repository)
+
+    let viewModel = HomeViewModel(useCase: useCase)
 
     let viewController = HomeViewController(viewModel: viewModel)
 

iOS/Projects/Features/Home/Sources/Presntaion/HomeScene/VIew/FeedImageCell.swift

@@ -6,6 +6,7 @@
 //  Copyright © 2023 kr.codesquad.boostcamp8. All rights reserved.
 //
 
+import Cacher
 import UIKit
 
 // MARK: - FeedImageCell
@@ -24,6 +25,12 @@ final class FeedImageCell: UICollectionViewCell {
     fatalError("cant use this init")
   }
 
+  override func prepareForReuse() {
+    super.prepareForReuse()
+
+    feedImage.image = nil
+  }
+
   private func setupViewHierarchyAndConstraints() {
     contentView.addSubview(feedImage)
     feedImage.topAnchor.constraint(equalTo: contentView.topAnchor).isActive = true
@@ -43,13 +50,15 @@ final class FeedImageCell: UICollectionViewCell {
     guard let imageURL else {
       return
     }
-
-    DispatchQueue.global().async {
-      guard let data = try? Data(contentsOf: imageURL) else { return }
-      DispatchQueue.main.async { [weak self] in
-        self?.feedImage.image = UIImage(data: data)
-        self?.layoutIfNeeded()
+    guard let data = MemoryCacheManager.shared.fetch(cacheKey: imageURL.absoluteString) else {
+      DispatchQueue.global().async {
+        guard let data = try? Data(contentsOf: imageURL) else { return }
+        DispatchQueue.main.async { [weak self] in
+          self?.feedImage.image = UIImage(data: data)
+        }
       }
+      return
     }
+    feedImage.image = UIImage(data: data)
   }
 }

iOS/Projects/Features/Home/Sources/Presntaion/HomeScene/VIew/FeedItemCollectionViewCell.swift

@@ -24,6 +24,12 @@ class FeedItemCollectionViewCell: UICollectionViewCell {
     fatalError("생성할 수 없습니다.")
   }
 
+  override func prepareForReuse() {
+    super.prepareForReuse()
+
+    profileImage.image = nil
+  }
+
   // MARK: - Property
 
   private var dataSource: UICollectionViewDiffableDataSource<Int, URL>? = nil
@@ -65,6 +71,7 @@ class FeedItemCollectionViewCell: UICollectionViewCell {
     label.text = "2023.12.07"
     label.font = .preferredFont(forTextStyle: .subheadline)
     label.textColor = DesignSystemColor.primaryText
+    label.contentMode = .scaleAspectFit
 
     label.translatesAutoresizingMaskIntoConstraints = false
     return label
@@ -310,10 +317,10 @@ extension FeedItemCollectionViewCell {
       return
     }
 
+    let url = url.compactMap { $0 }
     snapshot.deleteAllItems()
     snapshot.appendSections([0])
-    let url = url.compactMap { $0 }
-    snapshot.appendItems(Array(Set(url)), toSection: 0)
+    snapshot.appendItems(url, toSection: 0)
     dataSource?.apply(snapshot)
   }
 }