値オブジェクトのCodable対応

iOSDC Japan 2019のルーキーズLT枠で発表した資料です。

Transcript

1. 
   J04%$
   !NHVIJSP ஋ΦϒδΣΫτͷ $PEBCMFରԠ
2. ࣗݾ঺հ ‣ ໨ࠇ
   തོ
   
   !NBHVIJSP
   ‣ גࣜձࣾΧΧΫίϜ
   ‣ ৯΂ϩά
   
   ৯΂ϩά৽نࣄۀ
   ‣ J04ΞϓϦΤϯδχΞ
   
3. ࠓ೔࿩͢͜ͱ 4XJGUͰಋೖ͞Εͨ$PEBCMFΛར༻ͯ͠ ஋ΦϒδΣΫτΛؚΉܕʹ+40/σίʔυ ͨ͠ࡍͷରԠํ๏Λ͓࿩͠·͢
4. αϯϓϧίʔυ
5. struct User: Codable { let id: Int let name: String let age: Int } let json = """ { "id" : 1234, "name" : "maguhiro", "age" : 34 } """.data(using: .utf8)! let user = try! JSONDecoder() .decode(User.self, from: json) print("\(user.id)") // 1234
6. ໰୊ࣄྫ Ϣʔβʔ*%Λ୯७ͳ*OUܕͰఆٛͯ͠͠· ͏ͱɺҾ਺ʹϢʔβʔ*%Λ౉ؔ͢਺Ͱ ޡͬͯಉ͡*OUܕͰ͋Δଞͷ஋Λ౉ͯ͠͠ ·͏ڪΕ͕͋Γ·͢
7. class UserRepositoryImpl { func find(_ userID: Int) -> User? { // Կ͔͠Β͔ΒσʔλΛऔಘͯ͠ฦ٫ return user } } let userID = 1234 let photoID = 1000 let user = UserRepositoryImpl().find(photoID) // ↑ޡͬͯࣸਅIDΛҾ਺ʹ౉ͯ͠͠·͍ͬͯΔ
8. ͭΒ͍఺
9. ͲͪΒ΋ಉ͡ܕͳͷͰϏϧυ ΤϥʔɾϥϯλΠϜΤϥʔʹ ͳΒͳ͍
10. Ͳ͏ͳΕ͹
 خ͍͠ʁ
    
11. ϏϧυΤϥʔʹͳͬͯ͘Ε Δͱخ͍͠Ͱ͢ΑͶʁ
12. ͭ·Γ
13. Ϣʔβʔ*%Λද͢ܕ͕*OUܕͰ ͸ͳ͘ɺϢʔβʔ*%Ͱ͋Δࣄ Λࣔ͢ಠࣗͷܕͰఆ͍ٛͨ͠
14. ஋ΦϒδΣΫτΛ ಋೖ͠Α͏ʂ
    
15. ஋ΦϒδΣΫτͱ͸ʁ υϝΠϯۦಈઃܭ %%% ͷઓज़తઃܭͷ ཁૉͷҰͭɻಛ௃ͱͯ͠ҎԼͷΑ͏ͳ΋ ͷ͕͋Δɻ
    ‣ ෆมͰ͋Δ
    ‣ ஋ಉ࢜Ͱൺֱ͕Մೳ
    ‣ ަ׵Մೳ
16. ઌఔͷίʔυʹ
 ద༻ͯ͠ΈΑ͏
17. struct UserID: Codable { let value: Int init(value: Int) { self.value = value } } struct User: Codable { let id: UserID let name: String let age: Int }
18. class UserRepositoryImpl { func find(_ userID: UserID) -> User? { // Կ͔͠Β͔ΒσʔλΛऔಘͯ͠ฦ٫ return user } } let userID = UserID(value: 1234) let photoID = 1000 let user = UserRepositoryImpl().find(photoID) // ↑ޡͬͯࣸਅIDΛҾ਺ʹ౉͢ͱɺҎԼͷΑ͏ͳΤϥʔ͕ൃੜ͢Δ // Cannot convert value of type 'Int' to expected argument type 'UserID'
19. ޡͬͨར༻ʹ͙͢ ؾ͚ͮΔͧʂ
20. Ͱ͸ɺαϯϓϧͷ +40/σίʔυ
    ͯ͠ΈΑ͏ʂ
21. let json = """ { "id" : 1234, "name" : "maguhiro", "age" : 34 } """.data(using: .utf8)! let user = try! JSONDecoder() .decode(User.self, from: json) // Swift.DecodingError.typeMismatch(Swift.Dictionary<Sw ift.String, Any>, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "id", intValue: nil)], debugDescription: "Expected to decode Dictionary<String, Any> but found a number instead.", underlyingError: nil))
22. Τϥʔ͕ൃੜ
    
23. ஋ΦϒδΣΫτͱͯ͠6TFS*% ܕΛఆٛͨ͠ࣄͰɺσʔλߏ ଄ͷ֊૚͕ਂ͘ͳͬͯ͠·ͬ ͨͨΊ
24. Ͳ͏͢Ε͹ʁ
    
25. TJOHMF7BMVF$POUBJOFSΛ࢖͓͏ %FDPEFS
    &ODPEFSϓϩτίϧͰఆٛ͞ Ε͍ͯΔؔ਺
    ΦϑΟγϟϧυΩϡϝϯτʹ͸ҎԼͷΑ ͏ʹهࡌ͞Ε͍ͯΔɻ
    l୯ҰͷϓϦϛςΟϒ஋Λอ࣋͢Δͷʹద ͨ͠σίʔυɾΤϯίʔυίϯςφz
26. ࢖ͬͯΈΑ͏ʂ
    
27. ஋ΦϒδΣΫτΛ ද͢ϓϩτίϧͷ ࡞੒
28. protocol ValueObject: Codable, CustomStringConvertible, Equatable { associatedtype Value: Codable, CustomStringConvertible, Equatable var value: Value { get } init(value: Value) }
29. extension ValueObject { init(from decoder: Decoder) throws { let container = try decoder.singleValueContainer() let value = try container.decode(Value.self) self.init(value: value) } func encode(to encoder: Encoder) throws { var container = encoder.singleValueContainer() try container.encode(value) } var description: String { return value.description } static func == (lhs: Self, rhs: Self) -> Bool { return lhs.value == rhs.value } }
30. 6TFS*%ܕ΁ద༻
31. struct UserID: ValueObject { let value: Int init(value: Int) { self.value = value } }
32. let json = """ { "id" : 1234, "name" : "maguhiro", "age" : 34 } """.data(using: .utf8)! let user = try! JSONDecoder() .decode(User.self, from: json) print(“\(user.id)”) // 1234
33. ·ͱΊ ‣ ୯Ұͷ஋ΛΤϯίʔυɾσίʔυ͢Δ ৔߹ʹ͸ɺTJOHMF7BMVF$POUBJOFSΛ࢖ ͍·͠ΐ͏ʂ
    ‣ ஋ΦϒδΣΫτͷΤϯίʔυɾσίʔ υΛ࣮ݱ͠ޡͬͨར༻Λ๷͝͏ʂ
34. ͝ਗ਼ௌ͋Γ͕ͱ͏
    ͍͟͝·ͨ͠
    IUUQTHJUIVCDPNNBHVIJSP$PEBCMF4VQQPSU'PS7BMVF0CKFDU