MVVM+RAC+TDD

How to. For those who can.

1. HOW TO: MVVM + RAC + TDD Note: All info is subject to change. April 2015 1
2. ABOUT Alexey Demedeckiy iOS developer at Ciklum CSC CI Mentor 2
3. BACKGROUND B2B projects. Rich data flow. Rich UI. Animation driven UI. 3
4. AGENDA Road to MVVM MVVM State of the union TDD on UI? RAC? Outro 4
5. MASSIVE VIEW CONTROLLER UIViewController UIKit Network Data storage Business logic Custom interface System Interaction 5
6. APPLE MVC UIViewController UIKit Network Data storage Business logic Custom interface System Interaction 6
7. MVVM (RICH VIEW) UIViewController UIKit Network Data storage Business logic Custom interface System Interaction @interface MyView: UIView id<MyViewModel> 7
8. MVVM (RICH VIEW) UIViewController UIKit Network Data storage Business logic Custom interface System Interaction @interface MyView: UIView id<MyViewModel> 8
9. MVVM (RICH VIEW) + RAC UIViewController UIKit Network Data storage Business logic Custom interface System Interaction @interface MyView: UIView id<MyViewModel> 9
10. MVVM (RICH VIEW) + RAC UIViewController UIKit Network Data storage Business logic Custom interface System Interaction @interface MyView: UIView id<MyViewModel> 10
11. MVVM 2.0 11
12. ONE DIRECTION STATE FLOW Source Destination Data as @properties 12
13. NO HIDDEN CONNECTIONS Source Destination Data as @properties Call methods Set values 13
14. ONE DIRECTION EVENT FLOW Source Destination (void)[source callMethod] 14
15. NO SIDE EFFECTS Source Destination (void)[source callMethod] Return values Call methods 15
16. HOW TO ACHIEVE? Destination owns a Source. Destination calls a Source. Destination look at Source state. Destination is derived from Source. 16
17. AT SCALE D1 S2 S1 D2 System strong link 17
18. MVVM View Model ViewModel UIKit state flow event and ownership flow 18
19. AT SCALE No singletons. Context derived object graph. Lifecycle is determined by (UI + BL) 19
20. MVVM AT SCALE View Model ViewModel UIKit App component Creation 20
21. DECOMPOSITION IS A KEY View decomposed to UIViews, UIViewControllers, DataSources, Delegates, Managers, Storyboards… View Model decomposed to View Models. Model decomposed to Core, Services, Facades. 21
22. CODE / LAYER DISTRIBUTION 0 25 50 75 100 Content feed Content editor Offline content Offline with sync View ViewModel Model 22
23. VIEW LAYER Storyboard backed, XIB backed, code - no matter. Layout. Localization. Render efficiency. 23
24. VIEW LAYER CONNECTIONS View View Model Data display View View Model Alternate layout View View Model Tab like interface View View Model View Model 24
25. VIEW TESTING View Test ViewModel ViewModel Model App Acceptance testing Mock View Model Unit testing 25
26. TDD IN VIEW: SETUP 26
27. TDD IN VIEW: SETUP ARC Safe creation Window for events 27
28. TDD IN VIEW: DEALLOC 28
29. TDD IN VIEW: DEALLOC Expect dealloc RAC Dealloc hook Check dealloc ARC safe nil 29
30. TDD IN VIEW: RELOAD DATA 30
31. TDD IN VIEW: RELOAD DATA Flag HOOK on SUT method Check Set flag 31
32. TDD IN VIEW: CELL TAP Load mock data to table view 32
33. TDD IN VIEW: CELL TAP Setup expectation for correct call 33
34. TDD IN VIEW: CELL TAP Setup expectation for correct call Verify call correctness Fire expectation Is Equal to string wrapper 34
35. TDD IN VIEW: CELL TAP Send event to cell 35
36. TDD IN VIEW: CELL TAP Send event to cell Push segue require NavCon Wait for UIKit internals Send event Verify 36
37. TDD IN VIEW: P.S KIF for interacting. We need to wait. Sometimes. Test Behavior not code. 37
38. VIEWMODEL LAYER WD40 for your data. Intermediate view context. Umbrella for interfaces. Thin (5-15 % of code) 38
39. VIEWMODEL CONNECTIONS View Model Model View Model Model View Model Model View Model Model Core 39
40. VIEW MODEL TESTING TDD As simple as possible. Model state changes — ViewModel state changes ViewModel receive call — Model receive call Can hold more than one model. 40
41. MODEL LAYER Core F1 F2 F3 VM1 VM2 VM3 S1 S2 S3 41
42. FACADES Holding temporary contexts. Thin API Join several Core APIs. 42
43. FACADES: EXAMPLES Create new appointment in calendar. Write email. Fail possible action etc. 43
44. CORE Fail = Crash Minimum frameworks. (Core Data instances may be exceptions) Do not owns a facades. Owns services. Data consistence. 44
45. SERVICES All system API All frameworks. Request / Response API. No cross service communication. 45
46. MODEL: PS Can be simpler. Much simpler. 46
47. WHAT ABOUT BINDINGS? Any bindings is implementation detail. Cross layer usage. At least cross object. 47
48. KINDS OF MESSAGES: FROM: TO: Data Data Call Call Data 48
49. BINDINGS AS REACTIONS SOURCE: DESTINATION: State State Action Broadcast State 49
50. APPLE PUSH OPTIONS SOURCE: DESTINATION: set @property Setter Call method Method 50
51. APPLE PUSH OPTIONS SOURCE: DESTINATION: set @property Setter Call method Method Source is depend on Destination. Abstract layer depend on Concrete 51
52. APPLE PULL OPTIONS SOURCE: DESTINATION: KVO KVO - observe… NSNotification @selector() 52
53. APPLE PULL OPTIONS SOURCE: DESTINATION: KVO KVO - observe… NSNotification @selector() String based typing. Runtime error detection. Threads and ownership 53
54. RAC OPTIONS: SOURCE: DESTINATION: @property … RAC(…) = … rac_liftSelector: RACSignal* … RAC(…) = … 54
55. RAC USING 55
56. RAC USING: SUBSCRIBE NEXT Don’t 56
57. RAC USING: SUBSCRIBE NEXT rac_liftSelector RAC(…) Exception: -(RACSignal*)fn (limited context) 57
58. RAC USING: NO LOGIC INSIDE Do not mix with UIKit Do not mix with Networking Do not mix with Layout Do not mix with CoreData Do not mix with Threading 58
59. RAC USING: ABSTRACT TOOLS 59
60. RAC USING: ABSTRACT TOOLS 60
61. RAC USING: DECOMPOSE Fixing on instance Tech details Actual binding 61
62. RAC USING: DECOMPOSE 62
63. RAC USING: DECOMPOSE 63
64. RAC USING: DOUBLE WEAK 64
65. RAC USING: DOUBLE WEAK view not loaded yet first value missed replay value 65
66. RAC: PS Just glue. Powerful. Dangerous. 66
67. FUTURE ComponentsKit (@Facebook) Swift Implicit binding
68. LINKS http://cocoasamurai.blogspot.ca/2013/03/basic-mvvm-with- reactivecocoa.html https://speakerdeck.com/jspahrsummers/code-reuse-with-mvvm https://speakerdeck.com/dalog/m-v-vm-basics http://componentkit.org/ http://jlongster.com/Removing-User-Interface-Complexity,-or- Why-React-is-Awesome
69. QUESTIONS email: dalog@me.com skype: nobidon THE END 69