I'm using UIKit, Swift, just that is what I can use. And I'm making this: but I do not know if it is ok because I do not know how to implement it correctly my network is this : import UIKit import Foundation class NetworkManager { //  MARK: - ENUM NETWORKCONSTANTS   enum NetworkConstants {     static let urlString = "https://api.themoviedb.org/3/movie/popular?api_key=669056d94db324f563f195952deaede4&language=en-US&page=1"     static let imageUrlFirstPart = "https://image.tmdb.org/t/p/w500"   } //  MARK: - GETMOVIEDATA - URL AND PARSE FUNC   func getMovieData(completion: @escaping ([MovieData]) -> Void) {     guard let url = URL(string: NetworkConstants.urlString) else {       completion([])       return     }     let session = URLSession.shared     let dataTask = session.dataTask(with: url) { (data, response, error) in       guard error == nil, let dataResponse = response as? HTTPURLResponse, dataResponse.statusCode == 200, let data = data else {         completion([])         return       }       do {         let saveDataKey = "id"         var moviesData = [ResultsMovieModel]()         let decoder = JSONDecoder()         let movie = try decoder.decode(ResultsMovieModel.self, from: data)         let defaults = UserDefaults.standard         if let readData = defaults.data(forKey: saveDataKey) {           do {             moviesData = try decoder.decode([ResultsMovieModel].self, from: readData)           } catch {             print(error)           }         }         moviesData.append(movie)         let saveData = try JSONEncoder().encode(moviesData)         defaults.setValue(saveData, forKey: saveDataKey)         completion(movie.results)       } catch {         print(error)       }     }     dataTask.resume() //    let dataTask = session.dataTask(with: url) { (data, response, error) in //      guard error == nil, let dataResponse = response as? HTTPURLResponse, //         dataResponse.statusCode == 200, let data = data else { //        completion([]) //        return //      } //      guard let parsedData = try? decoder.decode(ResultsMovieModel.self, from: data) else { //        completion([]) //        return //      } //      if let saveDataUD = UserDefaults.standard.data(forKey: saveDataKey) { //        do { //          moviesData = try decoder.decode([ResultsMovieModel].self, from: saveDataUD) //        } catch { //          print(error) //        } //      } //      moviesData.append(parsedData) //      let saveData = try JSONEncoder().encode(moviesData) //      completion(parsedData.results) //    } //    dataTask.resume()   } //  MARK: - LOADMOVIEIMAGE FUNC   func loadMovieImage(backdropPath: String, completion: @escaping (UIImage) -> Void) {     let imageUrl = NetworkConstants.imageUrlFirstPart + backdropPath     guard let url = URL(string: imageUrl) else {       completion(UIImage(named: "artwork-source") ?? UIImage())       return     }     do {       let session = URLSession.shared       let task = session.dataTask(with: url) { data, response, error in         guard let dataResponse = data, let image = UIImage(data: dataResponse) else {           return         }         completion(image)       }       task.resume()     } //    let imageUrl = NetworkConstants.imageUrlFirstPart + backdropPath //    guard let url = URL(string: imageUrl) else { //      completion(UIImage(named: "artwork-source") ?? UIImage()) //      return //    } //    let session = URLSession.shared //    let task = session.dataTask(with: url) { data, response, error in //      guard let dataResponse = data, let image = UIImage(data: dataResponse) else { //        completion(UIImage(named: "artwork-source") ?? UIImage()) //        return //      } //      completion(image) //    } //    task.resume() //  } } }