a generic network call function

getData.swift

func getData<T: Codable>(endpoint: String, method: HTTPMethod?, params: [String: Any]?, headers: [String: String]?, model: T.Type, completion: @escaping (T?, URLResponse?, Error?) -> Void)
    {
        //1
        guard let url = URL(string: Constants.mainURLString.rawValue + endpoint) else {print("error with creating url"); return;}
        var request = URLRequest(url: url)
        
        //2
        request.httpMethod = method?.rawValue ?? "GET"
        
        //3
        if let headers = headers
        {
            for (key, value) in headers
            {
                request.addValue(value, forHTTPHeaderField: key)
            }
        }
        
        //4
        if let parameters = params
        {
            do
            {
                request.httpBody = try JSONSerialization.data(withJSONObject: parameters, options: .prettyPrinted)
                
            }
            catch let error
            {
                completion(nil, nil, error)
                return
            }
        }
        
        //5
        URLSession.shared.dataTask(with: request) { (data, response, error) in
            //6
            if error != nil
            {
                completion(nil, nil, error)
                return
            }
            
            //7
            do
            {
                let jsonData = try JSONDecoder().decode(model, from: data!)
                completion(jsonData, response, nil)
            }
            catch let error
            {
                completion(nil, nil, error)
            }
        }.resume()
    }