Being SOLID

MVVM, VIPER, MVC are quite different approaches to architecturing mobile applications. But they are based on several fundamental principles, like SOLID. Whatever architectural pattern you choose to use following these simple principles will help you write clean and maintainable code.

It's best to learn from mistakes. We are going to talk about each SOLID principle in the following way: "Violation of principle -> Discussion -> Refactoring". After this talk the audience should clearly understand how to apply SOLID principles to typical iOS development problems.

Transcript

1. Кто подставил Барбару Лисков? или Кто кого SOLID? Сергей Крапивенский, Rambler&Co
2. как сказал наш великий полководец Суворов “Do Not Learn Frameworks”
3. Фундаментальные знания
4. Фундаментальные знания Язык
5. Фундаментальные знания Язык Фреймворки
6. Фундаментальные знания Язык Фреймворки
7. RayWenderlich - driven development Senior ReactiveCocoa Developer Рамблер - секта VIPER
8. Фундаментальные знания Язык Фреймворки
9. Фундаментальные знания Язык Фреймворки
10. Фундаментальные знания Язык Фреймворки
11. Фундаментальные знания • Структуры данных • Алгоритмы • Паттерны • DRY, KISS, YAGNI • SOLID • И многое другое
13. Single responsibility principle Open-closed principle Liskov substitution principle Interface segregation principle Dependency inversion principle
14. Single Responsibility Principle “A class should have only one reason to change”
15. MassiveViewController 1.Ответственности сильно связаны 2.Класс перестает помещаться в голове 3.Тяжело поддерживать и тестировать
16. UITableViewController 1.Изменение логики работы с таблицей 2.Поменять иерархию вьюшек
17. UITableViewController Решение проблемы: не использовать его
18. Запуск приложения Push Notifications Quick Actions Уведомления о состояниях приложения Открытие по URL Фоновая загрузка данных AppDelegate
19. Запуск приложения Push Notifications Quick Actions Уведомления о состояниях приложения Открытие по URL Фоновая загрузка данных AppDelegate
20. AppDelegate Запуск приложения Quick Actions Поиск Push Notifications Открытие URL Состояния приложения Загрузка в фоне Handoff Extensions https://github.com/rambler-digital-solutions/RamblerAppDelegateProxy
21. SRP о снижении сложности
22. Single responsibility principle Open-closed principle Liskov substitution principle Interface segregation principle Dependency inversion principle
23. Open-Closed Principle “Software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification”
24. Простой и устойчивый дизайн
25. Новость Новость Новость Новость
26. Новость Новость Новость Новость Новость с фото Новость с фото
27. Новость Новость Новость Новость Новость с фото Новость с фото Реклама Реклама
28. } else ... return cell; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = [tableView dequeue...]; id model = [self modelAtIndex:indexPath.row]; if ([model isKindOfClass:[News class]]) { NewsCell *newsCell = (NewsCell *)cell; [newsCell setupWithNews:model]; } else if ([model isKindOfClass:[Advertisement class]]) { AdvertisementCell *adCell = (AdvertisementCell *)cell; [adCell setupWithAd:model];
29. } else ... return cell; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = [tableView dequeue...]; id model = [self modelAtIndex:indexPath.row]; if ([model isKindOfClass:[News class]]) { NewsCell *newsCell = (NewsCell *)cell; [newsCell setupWithNews:model]; } else if ([model isKindOfClass:[Advertisement class]]) { AdvertisementCell *adCell = (AdvertisementCell *)cell; [adCell setupWithAd:model];
30. } else ... return cell; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = [tableView dequeue...]; id model = [self modelAtIndex:indexPath.row]; if ([model isKindOfClass:[News class]]) { NewsCell *newsCell = (NewsCell *)cell; [newsCell setupWithNews:model]; } else if ([model isKindOfClass:[Advertisement class]]) { AdvertisementCell *adCell = (AdvertisementCell *)cell; [adCell setupWithAd:model];
31. } else ... return cell; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = [tableView dequeue...]; id model = [self modelAtIndex:indexPath.row]; if ([model isKindOfClass:[News class]]) { NewsCell *newsCell = (NewsCell *)cell; [newsCell setupWithNews:model]; } else if ([model isKindOfClass:[Advertisement class]]) { AdvertisementCell *adCell = (AdvertisementCell *)cell; [adCell setupWithAd:model];
32. } else ... return cell; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = [tableView dequeue...]; id model = [self modelAtIndex:indexPath.row]; if ([model isKindOfClass:[News class]]) { NewsCell *newsCell = (NewsCell *)cell; [newsCell setupWithNews:model]; } else if ([model isKindOfClass:[Advertisement class]]) { AdvertisementCell *adCell = (AdvertisementCell *)cell; [adCell setupWithAd:model];
34. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { id model = [self modelAtIndex:indexPath.row]; UITableViewCell<ConfigurableCell> *cell = ...; [cell configureWithObject:model]; return cell; }
35. NewsCell PhotoCell AdCell <ConfigurableCell> - (void)configure:(<CellObject>)object; - (Class)cellClass;
36. <ConfigurableCell> - (void)configure:(<CellObject>)object; News Photo Advert <CellObject> - (Class)cellClass;
37. <ConfigurableCell> - (void)configure:(<CellObject>)object; <CellObject> - (Class)cellClass;
38. Когда применять?
40. Single responsibility principle Open-closed principle Liskov substitution principle Interface segregation principle Dependency inversion principle
42. Liskov Substitution Principle “Subtypes must be substitutable for their base types”
43. Нужен для проверки корректности наследования
44. - (void)hideViews { [UIView animateWithDuration:1.0 animations:^ { for (UIView *view in self.animatableViews) { view.alpha = 0.5f; } }]; }
45. UIView UIVisualEffectView Всё ок ! <UIVisualEffectView> is being asked to animate its opacity. This will cause the effect to appear broken until opacity returns to 1
46. UIView UIVisualEffectView Всё ок ! <UIVisualEffectView> is being asked to animate its opacity. This will cause the effect to appear broken until opacity returns to 1
47. UIView UIVisualEffectView Всё ок ! <UIVisualEffectView> is being asked to animate its opacity. This will cause the effect to appear broken until opacity returns to 1
48. UIView UIVisualEffectView Всё ок ! <UIVisualEffectView> is being asked to animate its opacity. This will cause the effect to appear broken until opacity returns to 1
49. ¯\_(ϑ)_/¯
50. Single responsibility principle Open-closed principle Liskov substitution principle Interface segregation principle Dependency inversion principle
51. Interface Segregation Principle “Clients should not be forced to depend on methods that they do not use”
52. MailAPIClient - auth - findContact - getMailboxes - createMailbox - sendMail
53. MailAPIClient - auth - findContact - getMailboxes - createMailbox - sendMail Auth Contacts Mailboxes Messages
54. MailAPIClient - auth - findContact - getMailboxes - createMailbox - sendMail Auth Contacts Mailboxes Messages - auth - findContact - getMailboxes - createMailbox - sendMail - auth - findContact - getMailboxes - createMailbox - sendMail - auth - findContact - getMailboxes - createMailbox - sendMail - auth - findContact - getMailboxes - createMailbox - sendMail
55. AuthService MailboxService ContactService MessageService Auth Contacts Mailboxes Messages - auth - findContact - getMailboxes - createMailbox - sendMail - auth - findContact - getMailboxes - createMailbox - sendMail - auth - findContact - getMailboxes - createMailbox - sendMail - auth - findContact - getMailboxes - createMailbox - sendMail MailAPIClient
56. ISP - это не SRP
57. - sendSelfDestructMessage - deleteBothMessages ChatChannel - loadMessages - sendMessage - replyToMessage - forwardMessage - banUser - pinMessage
58. - sendSelfDestructMessage - deleteBothMessages ChatChannel - loadMessages - sendMessage - replyToMessage - forwardMessage Channel SecretChat Supergroup - banUser Group - pinMessage
59. - sendSelfDestructMessage - deleteBothMessages ChatChannel - loadMessages - sendMessage - replyToMessage - forwardMessage Channel SecretChat Supergroup - banUser Group - loadMessages - sendMessage - replyToMessage - forwardMessage - sendSelfDestruct - deleteBoth - pinMessage - banUser - pinMessage - loadMessages - sendMessage - replyToMessage - forwardMessage - sendSelfDestruct - deleteBoth - pinMessage - banUser - loadMessages - sendMessage - replyToMessage - forwardMessage - sendSelfDestruct - deleteBoth - pinMessage - banUser - loadMessages - sendMessage - replyToMessage - forwardMessage - sendSelfDestruct - deleteBoth - pinMessage - banUser
60. Single responsibility principle Open-closed principle Liskov substitution principle Interface segregation principle Dependency inversion principle
61. Dependency Inversion Principle “A. High-level modules should not depend on low-level modules. Both should depend on abstractions”
62. Dependency Inversion Principle “B. Abstractions should not depend on details. Details should depend on abstractions”
63. - (void)displayNews { NSPredicate *newsPredicate = ...; NSArray *news = [News MR_findAllWithPredicate:newsPredicate]; // Отображаем новости } Зависимость от Core Data
64. NewsViewController MagicalRecord "
65. NewsViewController MagicalRecord Realm "
66. NewsViewController MagicalRecord Realm "
67. @protocol NewsProvider <NSObject> - (NSArray *)obtainNewsForDate:(NSDate *)date; @end Зависимость от Core Data - (void)displayNews { NSDate *todayDate = ...; NSArray *news = [self.newsProvider obtainNewsForDate:todayDate]; // Отображаем новости }
68. @protocol NewsProvider <NSObject> - (NSArray *)obtainNewsForDate:(NSDate *)date; @end Зависимость от Core Data - (void)displayNews { NSDate *todayDate = ...; NSArray *news = [self.newsProvider obtainNewsForDate:todayDate]; // Отображаем новости }
69. @interface NewsViewController : UIViewController - (instancetype)initWithNewsProvider:(id<NewsProvider>)newsProvider; @end Зависимость от Core Data
70. NewsViewController <NewsProvider> MagicalRecord NewsProvider
71. NewsViewController <NewsProvider> Realm NewsProvider
72. Зависимости инвертированы #
73. Серебряной пули нет $
74. - Оноре де Бальзак “Обстоятельства переменчивы, принципы - никогда”