When I first started talking to people about wanting to work on backend services, the most common reaction was saying that it’s so different from iOS development. I never thought of it that way. Making iOS apps involves a lot of specialized knowledge applied to seemingly specialized problems. However, when those problems are distilled down to their fundamental form, they look similar to problems encountered in other software disciplines. Together we will discover those problems and learn how to apply them to different situations.

1. From iOS to
Distributed Systems
Michele Titolo
Lead Software Engineer, Capital One
@micheletitolo

2. 8 Months Ago I
Changed Teams
@micheletitolo

3. Mobile
BUT YOU’RE A
developer

4. @micheletitolo
What Are The Kinds
Of Problems I Solve
When Writing
Mobile Apps?

5. ‣ State
‣ Concurrency
‣ Instrumentation
‣ Testing
‣ Developer Efficiency
@micheletitolo

6. @micheletitolo
Distributed Systems

7. @micheletitolo
Mostly means
“microservices”

8. @micheletitolo
Single Responsibility

9. @micheletitolo
Production Ready Microservices
‣ Stability
‣ Reliability
‣ Scalability
‣ Fault Tolerance
‣ Performance
‣ Monitoring
‣ Documentation

10. ‣ State
‣ Concurrency
‣ Instrumentation
‣ Testing
‣ Developer Efficiency
@micheletitolo

11. @micheletitolo
State

12. @micheletitolo
iOS Apps Are Large
And Stateful

13. @micheletitolo
MassiveViewController

14. @micheletitolo
How To Fix?

15. @micheletitolo
Break Down Into
Functional Parts

16. @micheletitolo
Sounds Like A
Microservice

17. @micheletitolo
Inflexible Boundaries

18. @micheletitolo
Language Features

19. @micheletitolo
Dynamic
Weakly Typed

20. @micheletitolo
Why?

21. @micheletitolo
The Smaller The
Codebase, The Fewer
Language Features
Are Used

22. @micheletitolo
Focus On Simplicity

23. @micheletitolo
Generics: Great For
Modeling State

24. @micheletitolo
What If You Have No
State 🤔?

25. @micheletitolo
Protocols
Nil Checks

26. @micheletitolo
Shared State

27. @micheletitolo
Singletons

28. @micheletitolo
Dependency
Injection To The
Rescue

29. @micheletitolo
Translates To
Service Discovery

30. @micheletitolo
Register And Route
To Dependent
Services

31. @micheletitolo
Databases!

32. @micheletitolo
Kind Of Like
Singletons

33. @micheletitolo
Easy Reads
Restrict Writes

34. @micheletitolo
Read Replicas

35. @micheletitolo
Concurrency

36. @micheletitolo
iOS: 1 million users
each using 1 instance

37. @micheletitolo
Distributed Systems:
1 million users using
n instances

38. @micheletitolo
🙀

39. @micheletitolo
Concurrency Matters

40. @micheletitolo
Don’t Block The
Main Thread

41. @micheletitolo
Queues, Threads,
Callbacks All Matter

42. @micheletitolo
GCD is 💯

43. @micheletitolo
Other Languages
Are Not As
Sophisticated

44. @micheletitolo
Instrumentation

45. @micheletitolo
‣ Performance
‣ Usage

46. @micheletitolo
iOS Apps Are
Black Boxes

47. @micheletitolo
If It’s Not Tracked,
You Can’t Know

48. @micheletitolo
Knowing What To
Track Is Key

49. @micheletitolo
Apps Behave
Differently In
The Wild

50. @micheletitolo
Instrumentation
On iOS

51. @micheletitolo
Instruments.App
Helps Locally

52. @micheletitolo
AppStore
App Analytics

53. @micheletitolo
3rd Party Analytics

54. @micheletitolo
Microservices

55. @micheletitolo
Microservices Are
Also Black Boxes

56. @micheletitolo
Developers
Shouldn’t Have
Prod SSH Access

57. @micheletitolo
Alerts Need Metrics

58. @micheletitolo
Again, Local Dev Is
Different

59. @micheletitolo
Simulate Load In
Pre-Production

60. @micheletitolo
Imperfect, Imprecise

61. @micheletitolo
Instrumentation
Helps Surface And
Diagnose Issues

62. @micheletitolo
Testing

63. Unit
Integration
End
to End

64. @micheletitolo
Testing Is Universal

65. @micheletitolo
Testing On iOS

66. @micheletitolo
Isolated State

67. @micheletitolo
Dependency
Injection

68. @micheletitolo
Run Frequently

69. @micheletitolo
Tests For Everything

70. @micheletitolo
Microservices

71. @micheletitolo
But First One Thing I
Glossed Over…

72. @micheletitolo
Microservices Are
Infrastructure Heavy

73. @micheletitolo
CICD

74. @micheletitolo
If Code Goes To Prod
Basically Immediately…

75. @micheletitolo
Automate All The
Things

76. @micheletitolo
Codebase Needs
Lots Of Tests

77. @micheletitolo
Tests For
Microservices Need…

78. @micheletitolo
Isolated State

79. @micheletitolo
Dependency
Injection

80. @micheletitolo
All The Testing
Layers Covered

81. @micheletitolo
Just Like On iOS

82. @micheletitolo
Developer Efficiency

83. @micheletitolo
Move Fast
And
Break Things

84. @micheletitolo
Move Fast
And
Break Things

85. @micheletitolo
Move Fast
With
Stable Infra

86. @micheletitolo
Developers Like
Shipping

87. @micheletitolo
“It Works On My
Machine”

88. @micheletitolo
Codesigning 🙀

89. @micheletitolo
Fastlane 👍

90. @micheletitolo
Easy Releases ➡
Frequent Releases

91. @micheletitolo
Same For
Microservices

92. @micheletitolo
…If Not More

93. @micheletitolo
Automation ➡
Scaling

94. @micheletitolo
Software Moves Fast

95. @micheletitolo
To Summarize

96. @micheletitolo
Making iOS Apps
Requires Specialized
Knowledge

97. @micheletitolo
Rooted In
Fundamental Concepts

98. @micheletitolo
Different Tools

99. @micheletitolo
You Know More
Than You Think 🎉

100. Thank You
@micheletitolo
hi@michele.io

101. @micheletitolo
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