//
// ViewController.swift
// TargetActionUnitTests
//
// Created by Jonathan Rasmusson (Contractor) on 2020-05-08.
// Copyright © 2020 Jonathan Rasmusson. All rights reserved.
//
import UIKit
///
/// Model - Application data the is view agnostic.
///
/// This is business data. That has no concept of any particular view or how it will be used.
/// Account, User, Game. Often retrieved and populated from external service.
///
struct Game {
let name: String
let year: String
let author: String
}
///
/// View - What the user sees. `UIView` and `UIViewController` in iOS.
///
/// A UI friendly version of our Model data for this view.
struct GameViewData {
let name: String
}
class ViewController: UIViewController {
var button = makeButton(withText: "Start Game")
var label = makeLabel(withTitle: "Paused")
lazy var presenter = Presenter(with: self)
override func viewDidLoad() {
super.viewDidLoad()
layout()
}
func layout() {
button.addTarget(self, action: #selector(startGame(sender:)), for: .primaryActionTriggered)
view.addSubview(button)
view.addSubview(label)
button.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
button.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
label.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
label.topAnchor.constraint(equalToSystemSpacingBelow: button.bottomAnchor, multiplier: 3).isActive = true
}
@objc func startGame(sender: Any?) {
presenter.startGame()
}
}
///
/// Presenter - A mediator between the model the view.
///
/// The presenter takes events from the model and the view, and translates them
/// each into actions the other can understand. For example, business data may need to be
/// translated into view specific data the UI can understand (i.e. Game -> GameViewData).
class Presenter {
weak var view: PresenterView?
init(with view: PresenterView) {
self.view = view
}
let spaceInvaders = Game(name: "Space Invaders", year: "1978", author: "Tomohiro Nishikado")
@objc func startGame() {
let game = GameViewData(name: spaceInvaders.name)
view?.updateGame(game)
}
}
///
/// A UIKit agnostic protocol to talk back to the view.
///
/// The Presenter needs a way to talk back to the View and issue it commands.
/// This protocol is purposefully UIKit agnostic. So it has no dependencies
/// on underlying UI implementations.
///
protocol PresenterView: AnyObject {
func updateGame(_ model: GameViewData)
}
extension ViewController: PresenterView {
func updateGame(_ model: GameViewData) {
label.text = model.name
self.view.backgroundColor = .yellow
}
}
///
/// Factories
///
func makeButton(withText text: String) -> UIButton {
let button = UIButton()
button.translatesAutoresizingMaskIntoConstraints = false
button.setTitle(text, for: .normal)
button.titleLabel?.adjustsFontSizeToFitWidth = true
button.contentEdgeInsets = UIEdgeInsets(top: 8, left: 16, bottom: 8, right: 16)
button.backgroundColor = .systemBlue
button.layer.cornerRadius = 8
return button
}
func makeSymbolButton(systemName: String, target: Any, selector: Selector) -> UIButton {
let configuration = UIImage.SymbolConfiguration(scale: .large)
let image = UIImage(systemName: systemName, withConfiguration: configuration)
let button = UIButton()
button.translatesAutoresizingMaskIntoConstraints = false
button.addTarget(target, action: selector, for: .primaryActionTriggered)
button.setImage(image, for: .normal)
button.imageView?.contentMode = .scaleAspectFit
return button
}
func makeLabel() -> UILabel {
return makeLabel(withTitle: "")
}
func makeLabel(withTitle title: String) -> UILabel {
let label = UILabel()
label.translatesAutoresizingMaskIntoConstraints = false
label.text = title
label.textAlignment = .center
label.textColor = .black
label.numberOfLines = 0
label.adjustsFontSizeToFitWidth = true
return label
}This example shows one of two screens depending on how many users are created in the UserService class.
import UIKit
///
/// Model
///
struct User {
let firstName: String
let lastName: String
let age: Int
}
class UserService {
func getUsers(callBack: @escaping ([User]) -> Void){
// let users = [User(firstName: "Kevin", lastName: "Flynn", age: 36),
// User(firstName: "Alan", lastName: "Bradley", age: 24),
// User(firstName: "Ed", lastName: "Dilinger", age: 39)
// ]
let users = [User]()
let dispatchTime = DispatchTime.now() + Double(Int64(0.1 * Double(NSEC_PER_SEC))) / Double(NSEC_PER_SEC)
DispatchQueue.main.asyncAfter(deadline: dispatchTime, execute: {
callBack(users)
})
}
}
///
/// View
///
class ViewController: UIViewController {
lazy var userPresenter = UserPresenter(userService: UserService(), userView: self)
let cellId = "mvpCellId"
var tableView = UITableView()
var usersToDisplay = [UserViewData]()
override func viewDidLoad() {
super.viewDidLoad()
tableView.dataSource = self
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
userPresenter.getUsers()
}
override func loadView() {
view = tableView
}
}
extension ViewController: UITableViewDataSource {
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: UITableViewCell.CellStyle.subtitle, reuseIdentifier: cellId)
let userViewData = usersToDisplay[indexPath.row]
cell.textLabel?.text = userViewData.name
cell.detailTextLabel?.text = userViewData.age
return cell
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return usersToDisplay.count
}
}
extension ViewController: UserView {
func setUsers(users: [UserViewData]) {
usersToDisplay = users
tableView.reloadData()
}
func setEmptyUsers() {
view.backgroundColor = .systemRed
}
}
///
/// Presenter
///
// UI friendly model for the view.
struct UserViewData {
let name: String
let age: String
}
// A UIKit agnostic protocol to talk to the View.
protocol UserView: AnyObject {
func setUsers(users: [UserViewData])
func setEmptyUsers()
}
class UserPresenter {
private let userService: UserService
weak var userView: UserView?
init(userService: UserService, userView: UserView) {
self.userService = userService
self.userView = userView
}
func getUsers(){
userService.getUsers{ [weak self] users in
if users.count == 0 {
self?.userView?.setEmptyUsers()
} else {
let mappedUsers = users.map {
return UserViewData(name: "\($0.firstName) \($0.lastName)", age: "\($0.age) years")
}
self?.userView?.setUsers(users: mappedUsers)
}
}
}
}