Generics With Swift
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The document discusses generics in Swift. It provides examples of using generics to write functions that can swap or operate on values of any type rather than being limited to a specific type. The document compares generics to using protocols, noting some key differences in how the return value is handled. It also discusses challenges with using generics with some frameworks like TableViews due to bugs, as well as examples of using generics for things like API requests, object mapping, and completion handlers. Overall it advocates that generics are fast, useful, flexible and practical despite some limitations.
![Request<[User]>](https://image.slidesharecdn.com/generics-with-swift-150415225602-conversion-gate01/85/Generics-With-Swift-51-320.jpg)
Generics With Swift
- 1. Generics with Swift by akira hirakawa @akirahrkw
- 3. we use swift for Burpple app
- 6. Do you use Generics?
- 7. example
- 8. swap two Int values func swapTwoInts(inout a: Int, inout b: Int) { let temporaryA = a a = b b = temporaryA }
- 9. swap two Double values func swapTwoDoubles(inout a: Double, inout b: Double) { let temporaryA = a a = b b = temporaryA }
- 10. swap two String values func swapTwoStrings(inout a: String, inout b: String) { let temporaryA = a a = b b = temporaryA }
- 11. these are identical !!
- 13. generics !!
- 14. Generic function func swapTwoValues<T>(inout a: T, inout b: T) { let temporaryA = a a = b b = temporaryA }
- 15. swap Int values var someInt = 3 var anotherInt = 107 swapTwoValues(&someInt, &anotherInt)
- 16. swap String values var someString = "hello" var anotherString = "world" swapTwoValues(&someString, &anotherString)
- 17. can not var someInt = 3 var anotherString = "world" swapTwoValues(&someInt, &anotherString)
- 18. useful flexible
- 19. but
- 21. can
- 22. swap two Any values func swapTwoValues(inout a: Any, inout b: Any) { let temporaryA = a a = b b = temporaryA }
- 23. var a = 1 as Any var b = 2 as Any swapTwoValues(&a, &b)
- 24. var a = “a” as Any var b = “b” as Any swapTwoValues(&a, &b)
- 25. but
- 26. var a = 1 as Any var b = “a” as Any swapTwoValues(&a, &b)
- 27. which is better?
- 28. what is the difference?
- 29. func executeProtocol(p: Printable) -> Printable { } func executeGenerics<T: Printable>(p: T) -> T { }
- 30. almost same
- 31. func executProtocol(p: Printable) -> Printable { p.description return p } func executeGenerics<T: Printable>(p: T) -> T { p.description return p }
- 32. no difference?
- 33. return value
- 34. func executProtocol(p: Printable) -> Printable { return p } func executeGenerics<T: Printable>(p: T) -> T { return p }
- 35. -> Printable you need to cast to use the return value var movie: Movie = … var p: Printable = executProtocol(movie) (p as Movie).show()
- 36. -> T you don’t need to cast to use the value var movie: Movie = … movie = executeGenerics(movie) movie.show()
- 37. useful
- 38. different
- 39. performance?
- 41. case increment:
- 42. depends on -O and swift version
- 44. in practice?
- 45. case DataSource:
- 46. but
- 47. case DataSource:
- 48. Generics doesn’t work on TableViewDeleate, TableViewDataSource because of a bug ds.respondsToSelector(“tableView:numberOfRo wsInSection:”) is false http://www.openradar.me/radar? id=5829206453780480
- 49. case API Call:
- 50. Request<T>
- 51. Request<[User]>
- 52. Object Mapper
- 53. AnyObject -> T var orm = { (json: AnyObject) -> User in … … return user } var orm = { (json: AnyObject) -> Media in … … return media }
- 55. T -> () var handler = { ( item:User) -> () in … … } var handler = { (item:Media) -> () in … … }
- 57. I like generics :)
- 58. thanks
- 60. question?