let us: Go! 2022 summer https://github.com/iamchiwon/TheToDo

1. 송치원 (곰튀김)
iamchiwon.github.io
만들면서 느껴보는 POP
Realism Programmer
Protocol Oriented Programming

2. 내일 배포 전에
메뉴 기능 하나 없애 주세요

3. 내일 완공 전에
화장실 하나 없애 주세요
내일 배포 전에
메뉴 기능 하나 없애 주세요
VS
Hardware
Software

4. Software 답게 만들기
쉽게 변경할 수 있게 만들기

5. Protocol Oriented Programming
If someone is oriented towards or oriented to a particular thing or
person, they are mainly concerned with that thing or person.
oriented
[ ɔːrientɪd ]
ADJECTIVE

6. Protocol Oriented Programming

7. Object Oriented Programming

8. Protocol Basic

9. Delegate 만들기
protocol JsonFetcherDelegate : AnyObject {
func onFetched(json: String)
}
class JsonFetcher {
weak var delegate: JsonFetcherDelegate?
func fetch(url: String) {
guard let url = URL(string: url) else { return }
DispatchQueue.global(qos: .background).async {
if let data = try? Data(contentsOf: url),
let json = String(data: data, encoding: .utf8) {
self.delegate
?
.
onFetched(json: json)
}
}
}
}
class Main {
var fetcher : JsonFetcher {
let o = JsonFetcher()
o.delegate = self
return o
}
func main() {
fetcher.fetch(url: "
.
.
.
")
}
}
extension Main : JsonFetcherDelegate
{
func onFetched(json: String) {
print(json)
}
}

10. 구현 강제하기
protocol JsonFetcherDelegate : AnyObject {
func onFetched(json: String)
}
class JsonFetcher {
weak var delegate: JsonFetcherDelegate?
func fetch(url: String) {
guard let url = URL(string: url) else { return }
DispatchQueue.global(qos: .background).async {
if let data = try? Data(contentsOf: url),
let json = String(data: data, encoding: .utf8) {
self.delegate
?
.
onFetched(json: json)
}
}
}
}
class Main : JsonFetcherDelegate {
var fetcher : JsonFetcher {
let o = JsonFetcher()
o.delegate = self
return o
}
func main() {
fetcher.fetch(url: "
.
.
.
")
}
}

11. 기본구현 넣기
protocol TypePresentable {
func typeName()
-
>
String
}
extension TypePresentable {
func typeName()
-
>
String {
"(type(of: self))"
}
}
extension Int : TypePresentable {}
extension String : TypePresentable {}
print(42.typeName())
/
/
Int
print("Hello World".typeName())
/
/
String
struct MyStruct : TypePresentable {}
print(MyStruct().typeName())
/
/
MyStruct

12. 추상화 하기
protocol Repository {
func save(data: Data)
func load()
-
>
Data?
}
class MemRepository : Repository {
private var data: Data?
func save(data: Data) {
self.data = data
}
func load()
-
>
Data? {
return data
}
}
class FileRepository : Repository {
private var filePath: URL?
func save(data: Data) {
try! data.write(to: filePath!)
}
func load()
-
>
Data? {
return try? Data(contentsOf: filePath!)
}
}
Repository
MemRepository FileRepository

13. 느슨한 결합
protocol Repository {
func save(data: Data)
func load()
-
>
Data?
}
class MemRepository : Repository {
private var data: Data?
func save(data: Data) {
self.data = data
}
func load()
-
>
Data? {
return data
}
}
class ViewModel {
private let repository: Repository
init(repository: Repository) {
self.repository = repository
}
}
let viewModel = ViewModel(repository: MemRepository())
ViewModel Repository
MemRepository

14. Q. 다음 중 올바르지 않은 것은?
protocol A {
func a()
-
>
Int
}
protocol B {
func b<T: Numeric>()
-
>
T
}
protocol C<T: Numeric> {
func c()
-
>
T
}
protocol D {
associatedtype T: Numeric
func d()
-
>
T
}
1⃣ 2⃣
3⃣ 4⃣

15. 만들면서 느껴보기
1. 있다 치고
2. 알게 뭐야

16. TodoViewController
class ToDoViewController: UITableViewController {
let service: ToDoService
@IBAction func onCreateToDo(title: String) {
/
/
TODO: create TODO
tableView.reloadData()
}
}
extension ToDoViewController {
override func tableView(tableView:numberOfRowsInSection:)
-
>
Int {
/
/
TODO: get TODOs count
}
override func tableView(tableView:,cellForRowAt:)
-
>
UITableViewCell {
…
let index = indexPath.row
let item =
/
/
TODO: get TODO
cell.todo = item
return cell
}
}
TodoService
protocol ToDoService {
}

17. TodoViewController
class ToDoViewController: UITableViewController {
let service: ToDoService
@IBAction func onCreateToDo(title: String) {
service.create(title: title)
tableView.reloadData()
}
}
extension ToDoViewController {
override func tableView(tableView:numberOfRowsInSection:)
-
>
Int {
service.count()
}
override func tableView(tableView:,cellForRowAt:)
-
>
UITableViewCell {
…
let index = indexPath.row
let item = service.item(at: index)
cell.todo = item
return cell
}
}
TodoService
protocol ToDoService {
func create(title: String)
func count()
-
>
Int
func item(at: Int)
-
>
ToDo
}

18. ToDoItemTableViewCell
class ToDoItemTableViewCell: UITableViewCell {
@IBOutlet var isDone: UISwitch!
@IBOutlet var itemTitle: UILabel!
@IBOutlet var updatedAt: UILabel!
var toggable: Toggable?
@IBAction func onToggle() {
/
/
TODO: toggle done
}
}
Toggable
protocol Toggable {
}

19. ToDoItemTableViewCell
class ToDoItemTableViewCell: UITableViewCell {
@IBOutlet var isDone: UISwitch!
@IBOutlet var itemTitle: UILabel!
@IBOutlet var updatedAt: UILabel!
var toggable: Toggable?
@IBAction func onToggle() {
toggable
?
.
toggle(withId: todo.id)
}
}
Toggable
protocol Toggable {
func toggle(withId id: String)
}

20. ToDoServiceImpl
class ToDoServiceImpl: ToDoService {
private var todoItems: [ToDo] = []
func create(title: String) {
let todo = ToDo(id: UUID().uuidString,
title: title,
done: false,
createdAt: Date())
todoItems.append(todo)
}
func count()
-
>
Int {
return todoItems.count
}
func item(at index: Int)
-
>
ToDo {
return todoItems[index]
}
}
extension ToDoServiceImpl : Toggable {
func toggle(withId id: String) {
if let found = todoItems.enumerated()
.first(where: { $0.element.id
=
=
id }) {
let index = found.offset
var todo = found.element
todo.done = !todo.done
todoItems[index] = todo
}
}
}

21. TodoViewController
typealias ToDoToggableService = ToDoService & Toggable
class ToDoViewController: UITableViewController {
let service: ToDoToggableService
@IBAction func onCreateToDo(title: String) {
service.create(title: title)
tableView.reloadData()
}
}
extension ToDoViewController {
override func tableView(tableView:numberOfRowsInSection:)
-
>
Int {
service.count()
}
override func tableView(tableView:,cellForRowAt:)
-
>
UITableViewCell {
…
let index = indexPath.row
let item = service.item(at: index)
cell.todo = item
cell.toggable = service
return cell
}
}

22. ToDoServiceImpl
class ToDoServiceImpl: ToDoService {
private let repository: Repository
init(repository: Repository) {
self.repository = repository
/
/
TODO: load todos
}
deinit {
/
/
TODO: save todos
}
.
.
.
}
Repository
protocol Repository {
}

23. ToDoServiceImpl
class ToDoServiceImpl: ToDoService {
private let repository: Repository
init(repository: Repository) {
self.repository = repository
todoItems = repository.load()
}
deinit {
repository.save(todos: todoItems)
}
.
.
.
}
Repository
protocol Repository {
func load()
-
>
[ToDo]
func save(todos: [ToDo])
}

24. UserDefaultRepository
class UserDefaultRepository: Repository {
private let TodoKey = "todos"
func load()
-
>
[ToDo] {
guard let json = UserDefaults.standard.string(forKey: TodoKey),
let data = json.data(using: .utf8) else {
return []
}
return (try? JSONDecoder().decode([ToDo].self, from: data))
?
?
[]
}
func save(todos: [ToDo]) {
guard let data = try? JSONEncoder().encode(todos),
let json = String(data: data, encoding: .utf8) else {
return
}
UserDefaults.standard.set(json, forKey: TodoKey)
}
}

25. Codable
struct ToDo: Identifiable, Codable {
let id: String
let title: String
var done: Bool
let createdAt: Date
}
public protocol Decodable {
init(from decoder: Decoder) throws
}
public protocol Encodable {
func encode(to encoder: Encoder) throws
}
public typealias Codable = Decodable & Encodable

26. ToDoApp Overview
TodoViewController
UITableViewController
TodoService
TodoServiceImpl
Repository
UserDefaultRepository
Model
Toggable
ToDoItemTableViewCell
https://github.com/iamchiwon/TheToDo

27. Dependency Injection
class AppDelegate: UIResponder, UIApplicationDelegate {
let container = Container()
func application(application:,didFinishLaunchingWithOptions:)
-
>
Bool {
container.register(Repository.self) { _ in UserDefaultRepository() }
container.register(ToDoToggableService.self) { c in
let repository = c.resolve(Repository.self)!
return ToDoServiceImpl(repository: repository)
}
return true
}
}
func Inject<Service>(_ serviceType: Service.Type)
-
>
Service? {
(UIApplication.shared.delegate as? AppDelegate)
?
.
container.resolve(serviceType)
}
class ToDoListViewController: UITableViewController {
let service: ToDoToggableService = Inject(ToDoToggableService.self)!
.
.
.
}
https:
/
/
github.com/Swinject/Swinject

28. Q. 다음 중 올바르지 않은 것은?
protocol P {}
protocol PROTOCOL {}
extension PROTOCOL: P {}
protocol C {}
class CLASS {}
extension CLASS: C {}
protocol S {}
struct STRUCT {}
extension STRUCT: S {}
protocol E {}
enum ENUM {}
extension ENUM: E {}
1⃣ 2⃣
3⃣ 4⃣

29. 🤔 OOP 에서는 Protocol 의 역할이 많구나!
😏 그렇다면 Protocol을 더 적극적으로 써보자
🧐 class, struct, enum 전부 다 Protocol 적용하게 하자!
😠 Protocol이 진짜 중요해졌네!!!
😎 그렇다면 이제부터 Protocol을 중심으로 코딩해
🤩 그걸 Protocol Oriented Programming 이라고 하자
의식의 흐름

30. Summary
1. Protocol 로 할 수 있는 것들 == Protocol을 사용해서 얻는 이점
•Delegate
•구현 강제
•추상화
•느슨한 결합
➡ 유연한 확장
2. 구현 과정에서 구현체 보다 Protocol 을 우선해서 생각하자
3. POP == Protocol을 적극 활용하는 OOP
Oriented Programming