NYSwifty 2023 Slides: https://bit.ly/3ooZcK0

1. Mohammad Azam
Lessons Learned from Building
SwiftUI Apps
@azamsharp

2. About Me
• Mohammad Azam
• iOS Developer
• Coding bootcamp instructor
• Instructor on Udemy & LinkedIn
• Author and speaker

3. Agenda
• SwiftUI Architectures
• SwiftUI & Core Data
• Testing
• View Events
• Environment Slicing
• Evaluating vs Rendering
• SwiftUI & UIKit

4. This is NOT application
architecture advice!

9. Which pattern should I use?

10. https://www.linkedin.com/pulse/why-people-become-blind-followers-ameya-agrawal/

14. Client/Server
Apps

15. MovieListView MovieDetailScreen ReviewListScreen
AddReviewScreen
AddMovieScreen

16. MoveListViewModel
MovieViewModel
MovieDetailViewModel
AddMovieViewModel
ReviewListViewModel
ReviewViewModel
AddReviewViewModel

18. Dependency Injection

23. XAML
C#
WPF

24. AddMovieView

25. AddMovieView
! !

26. HTML Client Side Form Validation

27. AddMovieEditConfig

28. View is the View Model

29. Declaration of what
you want to be
displayed on the
screen
SwiftUI

30. Not actual HTML
elements. These are
Virtual DOM elements
managed by React.
React

31. Consuming API

32. @State and .task

33. Aggregate Root Model
WWDC 2020: Data Essentials in SwiftUI

34. Apple’s sample apps
Fruta and FoodTruck

36. Aggregate Root Model

37. @EnvironmentObjec
t

38. @EnvironmentObjec
t

39. MovieListViewModel
MovieViewModel
MovieDetailViewModel
AddMovieViewModel
ReviewListViewModel
ReviewViewModel
AddReviewViewModel
MVVM MV
Aggregate Model

40. Code is not an asset,
it is a liability

41. Bigger
Apps?

42. Multiple Aggregate Root objects based
on the bounded context of the application

45. Do your research!

47. MovieListView
AddMovieView
Sheet

48. onDismiss

49. NSFetchedResultsController

50. Don’t fight the framework?

51. @FetchRequest
@SectionedFetchRequest

54. NHibernate
LINQ to SQL
Entity Framework
Sequelize
Light Speed

55. Active Record Pattern

56. Base Model and Concrete Implementations

57. SwiftUI + Core Data
Active Record Pattern

58. Xcode Previews

59. Container Views
🙂
Structure your app for SwiftUI previews - WWDC20

61. Testin
g

63. LoginView Form Validation

64. But I really want to write a test!!!

65. LoginView

70. Don’t write unit test for your View Model to verify
the user interface.

72. 👎🏼

73. 👍🏼

74. Test behavior not implementation details

75. If the implementation details change, the test will fail

76. Don’t use mocks for managed dependency

78. Test is the isolation, not the thing under
test
- Ian Cooper

80. Rendering vs
Evaluation

81. body is being evaluated

82. The only view that is using
the @State count

83. SwiftUI does not recreate the
whole ContentView. It only
renders the views that needs
to be updated.

84. VStack
Text(“Counter”) Text(count
)
Button List
Simplified Tree representation of our ContentView

85. VStack
Text(“Counter”) Text(count
)
Button List
Only one of the Text views is using the @State count
property

86. VStack
Text(“Counter”) Text(count
)
Button List
SwiftUI destroys that view and recreates it again

95. Slicing Environment Objects

100. Programmatic Navigation

101. Programmatic Navigation
Usage

103. Date Formatting

104. List Formatting

106. Xcode Previews for UIKit

107. Injecting SwiftUI View into a UIKit App and Handling Events

108. Final thoughts
• SwiftUI is the future of app development
• Don’t fight the framework
• Read Apple’s documentation on SwiftUI
• Watch WWDC videos to get better understanding
• I don’t know which architecture is best. Try out different ones and see which
one works for your needs.

109. https://azamsharp.com/books
Free books

110. https://azamsharp.com/nyswifty2023
References & Slides
https://www.slideshare.net/secret/1QsYpS5AFGz3cu

111. Contact
• azamsharp@gmail.com
• @azamsharp
• www.azamsharp.com
• https://www.udemy.com/user/mohammad-azam-2/