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
   

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2. Lori Olson
   • lori@wndx.com
   • www.wndx.com
   • @wndxlori
   • Freelance developer,
   mentor, trainer
   • CANADA!
   

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3. KUDOS
   Changing the world, one Thank You at a time!
   kudosnow.com
   

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4. i Develop
   • Ruby (mostly)
   • Rails
   • iOS (RubyMotion)
   • JRuby
   • Javascript (some)
   • jQuery
   • Maps/Charts
   • Javascript Testing
   

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5. i Teach
   • Ruby on Rails for Real Developers
   (RoR4Real)
   • Rails for iOS Developers (Rails4iOS)
   • Ladies Learning Code - Ruby Introduction
   

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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
   

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7. The Task
   

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8. Why?
   Learning RubyMotion
   

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9. How?
   To rewrite a (mobile) web application
   as an iOS application
   

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10. What?
    Wells In My Back Yard
    

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11. The Challenges
    

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12. LOTS of data
    

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13. On a Map
    

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14. In a List (table)
    

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15. Filtering by Location
    

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16. How hard could it
    be?
    

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17. Oh, not that much data
    

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18. RubyMotion gems/DSL’s
    • Nitron
    • MotionDataWrapper
    • MotionModel
    • MotionMigrate
    • many, many others
    

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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?
    

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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
    

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21. iOS Basics
    • Ray Wenderlich!
    • http://www.raywenderlich.com/934/core-
    data-tutorial-for-ios-getting-started
    

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22. It’s not as scary as it looks
    

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23. What?
    • Models (entities) in code
    • Relationships in code
    • Loading data
    • Optimization
    

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24. Models in code
    

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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
    

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26. location.rb (model)
    

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27. location.rb (entity)
    

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28. location.rb (properties)
    

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29. location_store.rb (store)
    

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30. location_store.rb (MoM)
    

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31. location_store.rb (psc)
    

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32. location_store.rb (MoC)
    

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33. That was easy
    

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34. Or was it?
    

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36. Overly simplistic
    • Doesn’t work with multiple models with
    relationships
    • You need a reference to an entity, to define
    a relationship fully
    

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37. Chicken & Egg problem
    

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38. Relationships in code
    

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39. Solution
    • Define your entities. First.
    • Lazily! define your entities’ properties
    • properties = (attributes and relationships)
    

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40. Just the entity...
    

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41. MoC, lazily defined properties
    

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42. attributes
    

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43. attributes
    

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44. relationships
    

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45. relationships
    

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46. properties
    

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47. The “other” model
    

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48. Relationships
    • Done
    • With that, you can pretty much define any
    kind of model and relationship you want, in
    code, no magic required.
    

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49. Data Loading
    

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50. iOS Core Data Basics
    • Back to Ray
    • http://www.raywenderlich.com/12170/core-
    data-tutorial-how-to-preloadimport-
    existing-data-updated
    

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51. The RubyMotion way
    

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52. Read the data file (JSON)
    

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53. Add data to store
    

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54. add_bank
    

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55. That was easy
    

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56. Or was it?
    

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57. How many wells do I
    have to load again?
    

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58. 244,292
    Oh.
    

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59. Houston, we have a
    problem
    

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60. Read in the WHOLE file?
    

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61. save for every add?
    

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62. That won’t work either
    • add, add, add ...., save once
    

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63. Batching… ?
    • add, add, add, save, add, add, add, save
    

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64. Wait, what?
    

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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.
    

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66. New, improved load
    

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67. streaming (CSV) load
    

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68. create_bank (no save)
    

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69. saves, every 100
    progress every 100/1000
    

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70. Catch the odd ones
    

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71. Ta da!
    244,292 wells loaded
    

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72. And then your table
    view chokes on 244k
    items
    

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73. Optimization
    

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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
    

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75. Why?
    • NSFetchedResultsController gives us huge
    performance benefits
    • Avoids loading all the data in memory at
    once
    

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76. bank_store.rb
    

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77. failed_bank_table_view_controller.rb
    

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78. failed_bank_table_view_controller.rb
    

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79. number of rows
    

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80. cell for row
    

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81. configure cell
    

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82. the delegate
    

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84. In Summary
    • Create models in code
    • Create relationships between models in
    code
    • Pre-loading data
    • LOTS of data
    • Efficiently displaying data
    

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85. Please use Core Data!
    

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86. Core Data in Motion
    • It’s an ebook!
    • Almost finished!
    • http://coredatainmotion.com
    

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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
    

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