Core Data in RubyMotion - #inspect

Have you tried to use CoreData in RubyMotion, only to get lost in the quagmire of simplistic or confusing examples, DSL's and gems? Let's go out and shave that herd of yaks!

Transcript

1. Core Data in Motion RubyMotion #inspect May 28-29, 2014
2. Lori Olson • lori@wndx.com • www.wndx.com • @wndxlori • Freelance developer, mentor, trainer • CANADA!
3. KUDOS Changing the world, one Thank You at a time! kudosnow.com
4. i Develop • Ruby (mostly) • Rails • iOS (RubyMotion) • JRuby • Javascript (some) • jQuery • Maps/Charts • Javascript Testing
5. i Teach • Ruby on Rails for Real Developers (RoR4Real) • Rails for iOS Developers (Rails4iOS) • Ladies Learning Code - Ruby Introduction
6. i Speak • 2014 • Scottish Ruby Conference, RubyMotion #inspect • 2013 • RubyConf AU, NSScotland • 2012 • Confoo, RailsConf, Aloha RubyConf • 2011 • jQueryConf, Madison Ruby • 2010 • Conferencia Rails • 2009 • RailsConf
7. The Task
8. Why? Learning RubyMotion
9. How? To rewrite a (mobile) web application as an iOS application
10. What? Wells In My Back Yard
11. The Challenges
12. LOTS of data
13. On a Map
14. In a List (table)
15. Filtering by Location
16. How hard could it be?
17. Oh, not that much data
18. RubyMotion gems/DSL’s • Nitron • MotionDataWrapper • MotionModel • MotionMigrate • many, many others
19. Problems • RubyMotion gems/DSL’s hide a lot • Straight iOS Objective-C development relies on Xcode magic (hides a lot) • Complex data is complex • Large data is large • What do I do when I reach the limitations of these solutions?
20. The Real Problem • Sometimes you just need to understand how to solve problems at the most basic API code level, and the abstractions (and magic) just get in the way
21. iOS Basics • Ray Wenderlich! • http://www.raywenderlich.com/934/core- data-tutorial-for-ios-getting-started
22. It’s not as scary as it looks
23. What? • Models (entities) in code • Relationships in code • Loading data • Optimization
24. Models in code
25. Models in Code • Hey, isn’t there a sample app for that? • Locations • https://github.com/HipByte/ RubyMotionSamples/tree/master/ios/ Locations • MVCS pattern
26. location.rb (model)
27. location.rb (entity)
28. location.rb (properties)
29. location_store.rb (store)
30. location_store.rb (MoM)
31. location_store.rb (psc)
32. location_store.rb (MoC)
33. That was easy
34. Or was it?
36. Overly simplistic • Doesn’t work with multiple models with relationships • You need a reference to an entity, to define a relationship fully
37. Chicken & Egg problem
38. Relationships in code
39. Solution • Define your entities. First. • Lazily! define your entities’ properties • properties = (attributes and relationships)
40. Just the entity...
41. MoC, lazily defined properties
42. attributes
43. attributes
44. relationships
45. relationships
46. properties
47. The “other” model
48. Relationships • Done • With that, you can pretty much define any kind of model and relationship you want, in code, no magic required.
49. Data Loading
50. iOS Core Data Basics • Back to Ray • http://www.raywenderlich.com/12170/core- data-tutorial-how-to-preloadimport- existing-data-updated
51. The RubyMotion way
52. Read the data file (JSON)
53. Add data to store
54. add_bank
55. That was easy
56. Or was it?
57. How many wells do I have to load again?
58. 244,292 Oh.
59. Houston, we have a problem
60. Read in the WHOLE file?
61. save for every add?
62. That won’t work either • add, add, add ...., save once
63. Batching… ? • add, add, add, save, add, add, add, save
64. Wait, what?
65. Back to Core Data Basics • Thankfully, Ray figured that out. • Updated the tutorial to operate as an OS X (console) app. • RubyMotion can do that, too.
66. New, improved load
67. streaming (CSV) load
68. create_bank (no save)
69. saves, every 100 progress every 100/1000
70. Catch the odd ones
71. Ta da! 244,292 wells loaded
72. And then your table view chokes on 244k items
73. Optimization
74. Back to Basics (again) • Ray sure has a lot of good material, doesn’t he? • http://www.raywenderlich.com/999/core- data-tutorial-for-ios-how-to-use- nsfetchedresultscontroller
75. Why? • NSFetchedResultsController gives us huge performance benefits • Avoids loading all the data in memory at once
76. bank_store.rb
77. failed_bank_table_view_controller.rb
78. failed_bank_table_view_controller.rb
79. number of rows
80. cell for row
81. configure cell
82. the delegate
84. In Summary • Create models in code • Create relationships between models in code • Pre-loading data • LOTS of data • Efficiently displaying data
85. Please use Core Data!
86. Core Data in Motion • It’s an ebook! • Almost finished! • http://coredatainmotion.com
87. That’s All, Folks! • Code: 
 https://github.com/wndxlori/WNDXRubyMotion/ tree/master/FailedBankCD • Questions? Comments? • @wndxlori • lori@wndx.com • http://www.linkedin.com/in/loriolson • http://www.wndx.com