I am trying to load the image from url and show it into collection view cell. I am following MVVM . Here is the URL return single image https://picsum.photos/200 . I have set the cell with delegate and data source , I am not able to find out why the image is not reddening into collection view.

Here is the code for network layer..

import Foundation
import UIKit

enum ImageFetchingError: Error {
    case timeout
    case unknown
}

protocol CatImageCellModel {
    func fetchCatImage(completion: @escaping (Result<UIImage, ImageFetchingError>) -> Void)
}

class NetworkLayer: CatImageCellModel  {

    
    func fetchCatImage(completion: @escaping (Result<UIImage, ImageFetchingError>) -> Void) {
        
        
        let url = "https://picsum.photos/200"
        guard let _url = URL(string: url) else {
            return
        }
        
        URLSession.shared.dataTask(with: _url) { data, response, error in
            guard
                let data = data,
                let image = UIImage(data: data),
                let response = response as? HTTPURLResponse,
                response.statusCode >= 200 && response.statusCode < 300 else {
                completion(.failure(.unknown))
                return
            }
            completion(.success(image))
        }.resume()
    }
}

Here is the code for view model..

import Foundation
import UIKit


enum ImageViewModelState {
    case loading
    case loaded(UIImage)
    case error

    var images:  UIImage {
        switch self {
        case .loaded(let images):
            return images
        case .loading, .error:
            return UIImage()
        }
    }
}

class ViewModel {
    
    private let networkLayer: NetworkLayer
    public var image: UIImage = UIImage()
    var updatedState: (() -> Void)?
    
    init(networkLayer: NetworkLayer = NetworkLayer()) {
        self.networkLayer = networkLayer
    }
    
    var state: ImageViewModelState = .loading {
        didSet {
            updatedState?()
        }
    }
    
    func fatchImage() {
        networkLayer.fetchCatImage { [weak self] result in
            switch result {
            case .success(let image):
                self?.image = image
                self?.state = .loaded(image)
                print("Name of the Image: (image)")
            case .failure(let error):
                print(error.localizedDescription)
                self?.state = .error
            }
        }
    }
   }

Here is the code for view..

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
    
    @IBOutlet weak var collectionView: UICollectionView!
    private var viewModel = ViewModel()
   
    override func viewDidLoad() {
        super.viewDidLoad()
        viewModel.fatchImage()
        collectionView.delegate = self
        collectionView.dataSource = self
        viewModel.updatedState = { [weak self] in
            DispatchQueue.main.async {
                self?.collectionView.reloadData()

            }
        }
    }
    
    func collectionView(_ collectionView: UICollectionView,
                        numberOfItemsInSection section: Int) -> Int {
        return 1
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        //
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "myCell", for: indexPath) as! CollectionViewCell
        // return card
         let image = viewModel.image
        cell.imageView.image = image
        
        return cell
    }
}

Here is the cell code ..

import UIKit

class CollectionViewCell: UICollectionViewCell {
    
    @IBOutlet weak var imageView: UIImageView!
    
    override func prepareForReuse() {
        imageView = nil
        imageView?.alpha = 0.5
    }
}

Now is saying .. following error .

Here is the result when I run the app which is blank..

screenshot…
(https://i.sstatic.net/v8nKFZIo.png)