Swift - Return Generic Type/Data

I have URLSession shared instance that fetches data. It returns a generic type. Everything works fine when I'm fetching data from a server and displaying it. But when I fetch an image I need to return the Generic Type as the data. How can I return the generic type/data so that it can be used to create the image in the imageView?

UIImageView:

extension UIImageView {
    
    func loadImage(with url: URL) {
        
        if let cachedImage = imageCache.object(forKey: url.absoluteString as AnyObject) as? UIImage {
            self.image = cachedImage
            return
        }
        
        URLSessionManager.fetchData(with: url, isImageFetch: true) { (result: Result<Data, SessionDataTaskError>) in

            switch result {

            case .failure(let error):

                print(error)

            case .success(let data):

                guard let downloadedImage = UIImage(data: data) else {
                    print("image data is nil")
                    return
                }

                DispatchQueue.main.async{ [weak self] in

                    imageCache.setObject(downloadedImage, forKey: url.absoluteString as AnyObject)
                    self?.image = downloadedImage
                }
            }
        }
    }
}

URLSessionManager:

class URLSessionManager {
    
    static let shared = URLSessionManager()
    
    static func fetchData<T: Decodable>(with url: URL, isImageFetch: Bool = false, completion: @escaping (Result<T, SessionDataTaskError>)->Void) { // SessionDataTaskError is just an Enum
        
        URLSession.shared.dataTask(with: url) { (data, response, error) in
            
            if let error = error {
                completion(.failure(SessionDataTaskError.failedIssue(error)))
                return
            }
            
            guard let data = data else {
                completion(.failure(SessionDataTaskError.dataIsNil))
                return
            }
            
            if isImageFetch {

                // *** How can I return the generic type/data so that it can be used to create the image in the imageView? ***
                return
            }

            do {
                
                let genericType = try JSONDecoder().decode(T.self, from: data)
                
                completion(.success(genericType))
                
            } catch {
                
                completion(.failure(SessionDataTaskError.catchIssue(error)))
                
                guard let err = error as? DecodingError else {
                    debugPrint("decodingError-:", error)
                    return
                }
                
                switch err {
                case .typeMismatch(let key, let value):
                    print("decodingError-Mismatch: \(key), value \(value) and ERROR: \(error.localizedDescription)")
                case .valueNotFound(let key, let value):
                    print("decodingError-ValueNotFound: \(key), value \(value) and ERROR: \(error.localizedDescription)")
                case .keyNotFound(let key, let value):
                    print("decodingError-KeyNotFound(: \(key), value \(value) and ERROR: \(error.localizedDescription)")
                case .dataCorrupted(let key):
                    print("decodingError-DataCorrupted: \(key), and ERROR: \(error.localizedDescription)")
                default:
                    print("decodingError-UnknownError: \(error.localizedDescription)")
                }
            }
            
        }.resume()
    }
}