Display continuous feed of recent photos with metadata

SimpleFlickrBrowser/Extensions/String.swift

@@ -0,0 +1,16 @@
+//
+// Created by Maxim Berezhnoy on 26/11/2020.
+//
+// Copyright (c) 2020 rencevio. All rights reserved.
+
+import Foundation.NSDate
+
+extension String {
+    func toInt() -> Int? {
+        Int(self)
+    }
+
+    func toDate(formatter: DateFormatter) -> Date? {
+        formatter.date(from: self)
+    }
+}

SimpleFlickrBrowser/SimpleFlickrBrowser/AppDelegate.swift

@@ -10,8 +10,8 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     var window: UIWindow?
     let dependencies = RootDependencies()
 
-    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
-        let viewController = dependencies.createBrowserViewController()
+    func application(_: UIApplication, didFinishLaunchingWithOptions _: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
+        let viewController = dependencies.createFeedViewController()
 
         let navigationController = UINavigationController(rootViewController: viewController)
 
@@ -21,4 +21,8 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
 
         return true
     }
+
+    func application(_: UIApplication, handleEventsForBackgroundURLSession _: String, completionHandler: @escaping () -> Void) {
+        BackgroundURLSession.shared.set(onBackgroundEventsHandledCallback: completionHandler)
+    }
 }

SimpleFlickrBrowser/SimpleFlickrBrowser/Models/Photo.swift

@@ -3,11 +3,22 @@
 //
 // Copyright (c) 2020 rencevio. All rights reserved.
 
+import struct Foundation.Data
+import struct Foundation.Date
 import struct Foundation.URL
 
 struct Photo {
+    struct Metadata {
+        let views: Int
+        let tags: [String]
+        let ownerName: String
+        let dateTaken: Date
+    }
+
     typealias ID = String
 
     let id: ID
-    let imageURL: URL
+    let imageData: Data
+    let fullSizeImageURL: URL
+    let metadata: Metadata
 }

SimpleFlickrBrowser/SimpleFlickrBrowser/Network/BackgroundURLSession.swift

@@ -0,0 +1,117 @@
+//
+// Created by Maxim Berezhnoy on 29/11/2020.
+//
+// Copyright (c) 2020 rencevio. All rights reserved.
+
+import Foundation
+
+extension URLSession {
+    static let sharedBackground = BackgroundURLSession.shared
+}
+
+final class BackgroundURLSession {
+    static let shared = BackgroundURLSession()
+
+    private var onBackgroundEventsHandled: (() -> Void)?
+
+    private let operatingQueue = DispatchQueue(label: "\(BackgroundURLSession.self)OperatingQueue")
+
+    private let identifier = "\(BackgroundURLSession.self)Identifier"
+
+    private var runningTasks = [URLSessionTask: Completion]()
+
+    private lazy var session: URLSession = {
+        let configuration = URLSessionConfiguration.background(withIdentifier: identifier)
+
+        return URLSession(configuration: configuration, delegate: sessionDelegate, delegateQueue: nil)
+    }()
+
+    private lazy var sessionDelegate = {
+        BackgroundURLSessionDelegate(onTaskFinished: onTaskFinished(), onAllTasksFinished: onAllTasksFinished())
+    }()
+
+    private init() {}
+
+    func set(onBackgroundEventsHandledCallback: @escaping () -> Void) {
+        DispatchQueue.main.async { [weak self] in
+            self?.onBackgroundEventsHandled = onBackgroundEventsHandledCallback
+        }
+    }
+
+    private func onTaskFinished() -> (URLSessionTask, Data?, Error?) -> Void {
+        { [weak self] task, data, error in
+            self?.operatingQueue.async { [weak self] in
+                guard let self = self, let taskCallback = self.runningTasks[task] else {
+                    return
+                }
+
+                self.runningTasks.removeValue(forKey: task)
+
+                taskCallback(data, error)
+            }
+        }
+    }
+
+    private func onAllTasksFinished() -> () -> Void {
+        {
+            DispatchQueue.main.async { [weak self] in
+                self?.onBackgroundEventsHandled?()
+                self?.onBackgroundEventsHandled = nil
+            }
+        }
+    }
+}
+
+// MARK: - NetworkSession
+
+extension BackgroundURLSession: NetworkSession {
+    func getData(from url: URL, _ completion: @escaping Completion) {
+        let task = session.downloadTask(with: url)
+
+        operatingQueue.async { [weak self] in
+            self?.runningTasks[task] = completion
+        }
+
+        task.resume()
+    }
+}
+
+private final class BackgroundURLSessionDelegate: NSObject {
+    private let onTaskFinished: (URLSessionTask, Data?, Error?) -> Void
+    private let onAllTasksFinished: () -> Void
+
+    init(onTaskFinished: @escaping (URLSessionTask, Data?, Error?) -> Void, onAllTasksFinished: @escaping () -> Void) {
+        self.onTaskFinished = onTaskFinished
+        self.onAllTasksFinished = onAllTasksFinished
+    }
+}
+
+// MARK: - URLSessionDelegate
+
+extension BackgroundURLSessionDelegate: URLSessionDelegate {
+    func urlSessionDidFinishEvents(forBackgroundURLSession _: URLSession) {
+        onAllTasksFinished()
+    }
+}
+
+// MARK: - URLSessionTaskDelegate
+
+extension BackgroundURLSessionDelegate: URLSessionTaskDelegate {
+    func urlSession(_: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
+        onTaskFinished(task, nil, error)
+    }
+}
+
+// MARK: - URLSessionDownloadDelegate
+
+extension BackgroundURLSessionDelegate: URLSessionDownloadDelegate {
+    func urlSession(_: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
+        do {
+            let data = try Data(contentsOf: location)
+
+            onTaskFinished(downloadTask, data, nil)
+        } catch {
+            onTaskFinished(downloadTask, nil, error)
+        }
+    }
+}

SimpleFlickrBrowser/SimpleFlickrBrowser/Network/HttpClient.swift

@@ -7,7 +7,7 @@ import Foundation
 
 protocol HttpCommunicator {
     typealias Completion = (Result<Data, Http.RequestError>) -> Void
-    func get(url: URL, completion: @escaping Completion)
+    func get(url: URL, background: Bool, completion: @escaping Completion)
 }
 
 enum Http {
@@ -18,9 +18,12 @@ enum Http {
 
     final class Client: HttpCommunicator {
         private let urlSession = URLSession.shared
+        private let backgroundUrlSession = URLSession.sharedBackground
 
-        func get(url: URL, completion: @escaping Completion) {
-            let task = urlSession.dataTask(with: url) { data, _, error in
+        func get(url: URL, background: Bool, completion: @escaping Completion) {
+            let session: NetworkSession = background ? backgroundUrlSession : urlSession
+
+            session.getData(from: url) { data, error in
                 guard let data = data else {
                     if let error = error {
                         completion(.failure(.httpError(error)))
@@ -33,8 +36,6 @@ enum Http {
 
                 completion(.success(data))
             }
-
-            task.resume()
         }
     }
 }

SimpleFlickrBrowser/SimpleFlickrBrowser/Network/NetworkSession.swift

@@ -0,0 +1,20 @@
+//
+// Created by Maxim Berezhnoy on 29/11/2020.
+//
+// Copyright (c) 2020 rencevio. All rights reserved.
+
+import Foundation
+
+protocol NetworkSession {
+    typealias Completion = (Data?, Error?) -> Void
+
+    func getData(from url: URL, _ completion: @escaping Completion)
+}
+
+extension URLSession: NetworkSession {
+    func getData(from url: URL, _ completion: @escaping Completion) {
+        dataTask(with: url) { data, _, error in
+            completion(data, error)
+        }.resume()
+    }
+}

SimpleFlickrBrowser/SimpleFlickrBrowser/Resources/Info.plist

@@ -29,8 +29,6 @@
 	<key>UISupportedInterfaceOrientations</key>
 	<array>
 		<string>UIInterfaceOrientationPortrait</string>
-		<string>UIInterfaceOrientationLandscapeLeft</string>
-		<string>UIInterfaceOrientationLandscapeRight</string>
 	</array>
 	<key>UISupportedInterfaceOrientations~ipad</key>
 	<array>

SimpleFlickrBrowser/SimpleFlickrBrowser/RootDependencies.swift

@@ -12,13 +12,14 @@ final class RootDependencies {
         photoDataProvider = photoDataProviderFactory.createPhotoProvider()
 
         let photoCollectionFetcherFactory = FlickrCollectionFetcherFactory()
-        photoCollectionFetcher = photoCollectionFetcherFactory.createCollectionFetcher()
+        photoCollectionFetcher = photoCollectionFetcherFactory.createCollectionFetcher(photoDataProvider: photoDataProvider)
     }
 
-    func createBrowserViewController() -> BrowserViewController {
-        let browserFactory = BrowserFactory()
+    func createFeedViewController() -> FeedViewController {
+        let feedCellFactory = FeedCellFactory()
+        let feedFactory = FeedFactory(feedCellFactory: feedCellFactory)
 
-        return browserFactory.createViewController(
+        return feedFactory.createViewController(
             photoDataProvider: photoDataProvider,
             photoCollectionFetcher: photoCollectionFetcher
         )