Core Data in RubyMotion #inspect
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Core Data doesn't have to be hard. Step by step, learn how to use Core Data in code, creating models and relationships. Loading data and efficiently displaying that data.
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Core Data in RubyMotion #inspect
- 1. Core Data in Motion RubyMotion #inspect May 28-29, 2014
- 2. Lori Olson • [email protected] • www.wndx.com • @wndxlori • Freelance developer, mentor, trainer • CANADA!
- 3. KUDOS Changing the world, oneThankYou at a time! kudosnow.com Thanks to my client Kudos, for being understanding about my speaking engagements.
- 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
- 9. How? To rewrite a (mobile) web application as an iOS application
- 10. What? Wells In My BackYard
- 11. The Challenges
- 12. LOTS of data
- 13. On a Map
- 14. In a List (table)
- 16. How hard could it be?
- 17. Oh, not that much data 244,292
- 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
- 31. location_store.rb (psc) Persistent Store Coordinator
- 32. location_store.rb (MoC) Managed Object Context
- 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
- 39. Solution • Define your entities. First. • Lazily! define your entities’ properties • properties = (attributes and relationships)
- 40. Just the entity... Wait a minute...
- 41. MoC, lazily defined properties
- 42. attributes
- 43. attributes
- 44. relationships
- 45. relationships
- 46. properties
- 47. The “other” model More of the same
- 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 But of course, his way is the Xcode way. We need to translate to RubyMotion.
- 51. The RubyMotion way Inside our store, create a load method
- 52. Read the data file (JSON)
- 53. Add data to store Wait, what does add_bank do again?
- 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? add, save, add, save
- 62. That won’t work either • add, add, add ...., save once Ok, no, that won’t work either
- 63. Batching… ? • add, add, add, save, add, add, add, save Looked promising, but still ended up with out of memory errors
- 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. Instead of running INSIDE the simulator (in your device)
- 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
- 78. failed_bank_table_view_controller.rb wall of text. let’s break that down
- 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! Finnegan!
- 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 • [email protected] • http://www.linkedin.com/in/loriolson • http://www.wndx.com