Alamofire + Codable

API.swift

class API {
    static let apiKey = "test"
    static let baseUrl = ""
    
    enum Endpoint {
        case login
        case register
        
        var endpoint: String {
            switch self {
            case .login:
                return "login"
            case .register:
                return "register"
            }
        }
    }
    
    static func createUrl(endpoint: Endpoint) -> String {
        return "\(API.baseUrl)\(endpoint.endpoint)"
    }
}

APIRepresentable.swift

import Foundation
import Alamofire

protocol APIRequestRepresentable {
    associatedtype CodableType: APIModelCodable
    
    static var method: Alamofire.HTTPMethod { get set }
    static var endpoint: API.Endpoint { get set }
    static func request(parameters: Codable?, completion: @escaping (_ object: CodableType?, _ error: ErrorResponse?) -> Void)
    static func defaultHeaderObject() -> DefaultHeader
    static func defaultHeader() -> HTTPHeaders
    static func tokenHeader(token: String) -> HTTPHeaders
    static func url() -> String
}

extension APIRequestRepresentable {
    static func defaultHeaderObject() -> DefaultHeader {
        return DefaultHeader(contentType: "application/json; charset=utf-8", apiKey: API.apiKey)
    }
    
    static func defaultHeader() -> HTTPHeaders {
        return defaultHeaderObject().asStringValueDictionary()
    }
    
    static func tokenHeader(token: String) -> HTTPHeaders {
        return TokenHeader(defaultHeader: defaultHeaderObject(), token: "Bearer \(token)").asStringValueDictionary()
    }
    
    static func url() -> String {
        return API.createUrl(endpoint: endpoint)
    }
    
    static func request(parameters: Codable?, completion: @escaping (_ object: CodableType?, _ error: ErrorResponse?) -> Void) {
        AlamoHelper.manager.request(
            url(),
            method: method,
            parameters: parameters?.asDictionary(),
            encoding: JSONEncoding.default,
            headers: defaultHeader()).responseJSON { response in
                //each response should have a status code and a json value
                guard let statusCode = response.response?.statusCode else {
                    completion(nil, ErrorResponse(reason: "Could not get status code"))
                    return
                }
                
                guard let jsonValue = response.result.value else {
                    completion(nil, ErrorResponse(reason: "Could not get JSON value"))
                    return
                }
                
                guard let data = try? JSONSerialization.data(withJSONObject: jsonValue) else {
                    completion(nil, ErrorResponse(reason: "Could not parse data"))
                    return
                }
                
                if 200...299 ~= statusCode {
                    //success
                    completion(CodableType.from(data: data), nil)
                } else {
                    //error - we need a JSONDecoder here because `ErrorResponse` does not conform to APIModel
                    completion(nil, try? JSONDecoder().decode(ErrorResponse.self, from: data))
                }
        }
    }
}

LoginRequest.swift

import Foundation
import Alamofire
import SwiftyJSON

struct LoginRequest: APIRequestRepresentable {
    typealias CodableType = User
    static var method: Alamofire.HTTPMethod = .post
    static var endpoint: API.Endpoint = .login
}

Model.swift

import Foundation

protocol APIModel {
    var id: Int { get set }
}

typealias APIModelCodable = APIModel & Codable

extension APIModel where Self: Codable {
    static func from(json: String, using encoding: String.Encoding = .utf8) -> Self? {
        guard let data = json.data(using: encoding) else { return nil }
        return from(data: data)
    }
    
    static func from(data: Data) -> Self? {
        let decoder = JSONDecoder()
        decoder.dateDecodingStrategy = .iso8601
        return try? decoder.decode(Self.self, from: data)
    }
    
    var jsonData: Data? {
        let encoder = JSONEncoder()
        encoder.dateEncodingStrategy = .iso8601
        return try? encoder.encode(self)
    }
    
    var jsonString: String? {
        guard let data = self.jsonData else { return nil }
        return String(data: data, encoding: .utf8)
    }
}

User.swift

import Foundation

struct User: APIModelCodable {
    var id: Int
    var name: String
    var email: String
    var admin: Bool
    var token: String
}

ViewController.swift

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        let loginRequest = Login(email: "email@email.com", password: "password")
        LoginRequest.request(parameters: loginRequest) { (user, error) in
            //`user` is of type `User` thanks to the typealias declaration in `LoginRequest`
        }
    }
}

How can this be adapted to return a collection of models? For example if you were to get all users for instance?

AlamoHelper and DefaultHeader are missing..

great gist , but like the others will search for the AlamoHelper idea