Types in Swift

Transcript

1. ܕ
   <UZQF> @yashigani Cocoaษڧձؔ੢ #60

2. yashigani id:yashigani_w @yashigani Mobile Application Engineer http://yashigani.hatenablog.com Hatena

3. https://flic.kr/p/nBzE6V ܕʹϋϚͬͨ͜ͱ͸͋Γ·͔͢ • ίϯύΠϧΤϥʔʹͳΔ΍ͭͰ͠ΐʁ • ܕ੍ͬͯ໿ͳ͚ͩͰͱʹ͔͘अຐ • id࠷ߴ΍Μʂʂʂܕͱ͔͍ΒΜʂʂʂ

4. ܕͬͯԿʁ

5. ܕ͸ৼΔ෣͍

6. ৼΔ෣͍ • ৼΔ෣͍ = σʔλߏ଄ + ॲཧ • Ͳ͏͍͏σʔλ͕Ͳ͏ಈ࡞͢Δ͔༧૝Ͱ͖Δ •

   ΠϯλʔϑΣʔε͕ݫ֨

7. $

8. ΞυϨε௕ͷϝλσʔλ • ϝϞϦۭؒʹ͓͚Δม਺ͷҐஔ • ௿ϨΠϠͷॲཧ͕Մೳͳނ • ϓϦϛςΟϒ͗͢Δ

9. 0CKFDUJWF$

10. ৼΔ෣͍ͷϝλσʔλ • isaϙΠϯλ • ม਺͕ৼΔ෣͏΂͖͜ͱΛࣔࠦ(ಈతσΟεύον) • ͨͩ͠ඞͣ͠΋ै͑Δͱ͸ݶΒͳ͍ • ม਺ͷৼΔ෣͍Λଋറ͢Δ΋ͷͰ͸ແ͍

11. 4XJGU

12. ৼΔ෣͍Λ໿ଋ͢Δ΋ͷ • ৼΔ෣͍Λม਺ʹଋറ • ͋Δܕͷม਺͸ͦͷܕͷৼΔ෣͍͔͠͠ͳ͍ • ܕͷ͋Δϓϩάϥϛϯά͕Մೳ

13. ͳͥϓϩάϥϜʹ ܕ͕ඞཁͳͷ͔

14. ܕ ܕ͕͋Δ͔ΒɺܕഁΓɻ
    ܕ͕ͳ͚Ε͹୯ͳΔʮܗແ͠ʯ ʕ
    ेീ୅໨
    தଜצࡾ࿠ Վ෣ب໾ऀ

15. /4%JDUJPOBSZ

16. NSDictionary *user = //... NSString *name = user[@"name"];

17. NSDictionary *user = //... NSString *name; if ([user[@"name"] isKindOfClass: [NSString

    class]]) { //!!!!! name = user[@"name"]; } else { //!!!!! }

18. https://flic.kr/p/7BD2UE Too bad ߏ଄͕ෆ໌ͳͷͰσʔλͷଘࡏΛஅఆͰ͖ͳ͍ Կ͕ೖ͍ͬͯΔͷ͔ෆ໌ͳͷͰσʔλܕΛࢦఆ ৼΔ෣͍͕ແ͍

19. ܕ͕ແ͍

20. .PEFM
    0CKFDU
    JO
    0CKFDUJWF$

21. @interface User : NSObject @property (copy) NSString *name; @property NSUInteger

    age; @property (getter=isPremium) BOOL premium; @end

22. User *user = //... UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@" cell"];

    cell.textLabel.text = user.name;

23. User *user = //... UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@" cell"];

    if (user.name != nil) { cell.textLabel.text = user.name; } else { //!!!!! }

24. https://flic.kr/p/i74K6M Too bad σʔλͷߏ଄ͱܕ͸දݱͰ͖ͨ ΠϯλʔϑΣʔε͕ෆఆ(nilͷՄೳੑ) ৼΔ෣͍͚͕ͩ͋Δ(ଋറ͕ແ͍)

25. ܗແ͠

26. .PEFM
    0CKFDU
    JO
    4XJGU

27. struct User { let name: String let age: Int let

    isPremium: Bool }

28. let user = //... let cell = tableView.dequeueReusableCellWithId entifier("cell") cell?.titleLabel.text

    = user.name

29. https://flic.kr/p/egaNwP Relaxed ෆ֬ఆͳཁૉ͸ϏδωεϩδοΫʹӅṭ ΞϓϦέʔγϣϯ͸σʔλΛදࣔ͢Δ͚ͩ ৼΔ෣͍Λଋറ͢Δ͜ͱͰ໿ଋ͞Εͨڍಈ

30. 5IJT
    JT
    ܕ

31. ܕͷ͋ΔϓϩάϥϜ • ৼΔ෣͍͕໌֬Ͱ׬શ • ͕ͨͬͯ͠ෆඞཁͳ৺഑͕͍Βͳ͍ • ϏδωεϩδοΫͱΞϓϦέʔγϣϯͷ෼཭ • ΠϯλʔϑΣʔεͷΈʹґଘ࣮ͨ͠૷

32. 0OF
    NPSF
    UIJOH

33. func parse(JSON: AnyObject?) -> (User?, NSError?) let JSON: AnyObject? =

    //... let (user, error) = parse(JSON) if let e = error { //... return } if let u = user { //... } else { // maybe user is nil... }

34. https://flic.kr/p/DC3Q Too bad user΋error΋nilͷͱ͖͸Ͳ͏͍͏Τϥʔʁ ΋ͬͱ΋ͬͱstrictʹදݱ͍ͨ͠ (User?, NSError?)͸ૉ๿͗͢Δ

35. ܕΛഁΔ
    ܕʹΑΔܕͷந৅Խ

36. 3FTVMU5

37. enum Result<T> { case Success(T) case Failure(NSError) init(_ value: T)

    { self = .Success(value) } init(_ error: NSError) { self = .Failure(error) } }

38. ܕഁΓٕ
    ͦͷ
    ʙHFOFSJDTʙ

39. enum Result<T> { case Success(T) case Failure(NSError) init(_ value: T)

    { self = .Success(value) } init(_ error: NSError) { self = .Failure(error) } } generics

40. ҦΘ͹ϫΠϧυΧʔυܕ • ͱΓ͋͑ͣ͸ͳΜͰ΋ೖΕΒΕΔܕ • ಉ͡ϥϕϧͷ΋ͷ͸ಉ͡ܕ • ΠϯλʔϑΣʔεΛܾΊͨͱ͖ʹܕ͕ܾ·Δ • func parse(_:AnyObject)

    -> Result<User> • Any/AnyObjectͱҧͬͯղ͘ͱ͖ʹ౎౓ͳʹ͔
 ͔֬ΊΔඞཁ͕ແ͍

41. ܕഁΓٕ
    ͦͷ
    ʙFOVNʙ

42. enum Result<T> { case Success(T) case Failure(NSError) init(_ value: T)

    { self = .Success(value) } init(_ error: NSError) { self = .Failure(error) } } enum

43. ෳ਺ͷঢ়ଶΛऔΓ͏Δ • Aঢ়ଶͳΒaΛ࣋ͬͯΔ͚ͲɼBঢ়ଶͰ͸࣋ͬͯͳ͍ • ͱΓ͋͑ͣAnyObjectʹͿͪࠐ·ͳ͍͍ͯ͘ • ͲΕ͔ͻͱͭͷঢ়ଶ͔͠औΓಘͳ͍ • A͔ͭBͳঢ়ଶ͸ଘࡏ͠ͳ͍

44. ͭ·ΓResultͱ͸ • ੒ޭ͔ࣦഊ͔ΛऔΓ͏Δ஋ • ੒ޭͨ͠ΒT͕ɼࣦഊͨ͠ΒNSError͕ಘΒΕΔ • ୯७ʹOptional஋Λฒ΂Δͷʹൺ΂ͯѻ͍΍͍͢ • ྆ํ஋͕͋Δ྆ํແ͍ͳΜͯ͜ͱ͸͋Γ͑ͳ͍

45. func parse(JSON: AnyObject?) -> Result<User> let JSON: AnyObject? = //

    ... let result = parse(JSON) switch result { case .Success(let user): // ... case .Failure(let error): // ... }

46. +VTU
    B
    &JUIFS

47. 0QUJPOBM

48. Optional΋ಉྨ • Optional͸ͻͱͭͷgenericܕΛऔΔenum • enum Optional<T> • ͳʹ͔ͷ஋͕͋Δ/ͳ͍ͷ2छྨͷঢ়ଶΛऔΓ͏Δ • SomeͩͬͨΒTΛ࣋ͬͯΔ

    • NoneͩͬͨΒnilΛ࣋ͬͯΔ

49. 5IJT
    JT
    ܕഁΓ

50. ·ͱΊ

51. 
    ܕ͸ৼΔ෣͍ͱ஌Δ
    
    ܕͷ͋ΔϓϩάϥϜ
    
    ܕΛഁΔ

52. ͋Γ͕ͱ͏͍͟͝·ͨ͠