Swiftのas Any / AnyObjectの暗黙的な型変換について

Zenn
- https://zenn.dev/yusuga/articles/c1e300d398e463

引用元
- Objective-C and Swift interoperability
https://rderik.com/blog/understanding-objective-c-and-swift-interoperability/

- Objective-C id as Swift Any
https://developer.apple.com/swift/blog/?id=39

- swift/stdlib/public/runtime/SwiftValue.h https://github.com/apple/swift/blob/main/stdlib/public/runtime/SwiftValue.h#L28-L31

- func _bridgeAnythingToObjectiveC
https://github.com/apple/swift/blob/a1e717223fcec87c35bff625175c39cfeec6d444/stdlib/public/core/BridgeObjectiveC.swift#L795-L827

- ObjectIdentifier
https://developer.apple.com/documentation/swift/objectidentifier

- Builtin.AnyObject
https://github.com/apple/swift/search?p=2&q=%22typealias+anyobject%22

Transcript

1. Swiftͷas Any / AnyObjectͷ
   ҉໧తͳܕม׵ʹ͍ͭͯ
   iPhone Dev SapporoษڧձΦϯϥΠϯ Mar, 2022
   1
   

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2. ੁݪ ༞
   @yusuga_
   2
   

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3. ໰୊1
   let int: Int = 0
   print(type(of: int)) // Int
   print(type(of: int as AnyObject)) // ԿʹͳΔʁ
   3
   

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4. ౴͑1
   let int: Int = 0
   print(type(of: int)) // Int
   print(type(of: int as AnyObject)) // __NSCFNumber
   __NSCFNumber
   ≒ NSNumber
   4
   

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5. ໰୊2
   let string = ""
   print(type(of: string)) // String
   print(type(of: string as AnyObject)) // ԿʹͳΔʁ
   5
   

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6. ౴͑2
   let string = ""
   print(type(of: string)) // String
   print(type(of: string as AnyObject)) // __NSCFConstantString
   __NSCFConstantString
   ≒ NSString
   6
   

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7. ͳ͔ͥObjectice-Cܥͷܕʹ
   ม׵͞Ε͍ͯΔͧʂ
   !
   7
   

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8. ໭͢͜ͱ΋Մೳ
   let int: Int = 0
   type(of: (int as AnyObject) as! Int) // Int
   8
   

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9. ໰୊3
   struct StructModel {}
   let structModel = StructModel()
   type(of: structModel) // StructModel
   type(of: structModel as AnyObject) // ԿʹͳΔʁ
   9
   

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10. ౴͑3
    struct StructModel {}
    let structModel = StructModel()
    type(of: structModel) // StructModel
    type(of: structModel as AnyObject) // __SwiftValue
    __SwiftValue
    10
    

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11. __SwiftValue
    !
    11
    

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12. ղઆ
    12
    

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13. SwiftͱObjective-Cͷܕͷ૬ޓม׵
    13
    

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14. SwiftͱObjective-Cͷܕͷ૬ޓม׵
    • Objective-C and Swift interoperabilityʢ૬ޓӡ༻ੑʣʹΑͬͯɺ
    SwiftͱObjective-CͷܕΛ૬ޓʹม׵͕ߦ͑Δ࢓༷ʹͳ͍ͬͯ
    Δɻ
    13
    

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15. SwiftͱObjective-Cͷܕͷ૬ޓม׵
    • Objective-C and Swift interoperabilityʢ૬ޓӡ༻ੑʣʹΑͬͯɺ
    SwiftͱObjective-CͷܕΛ૬ޓʹม׵͕ߦ͑Δ࢓༷ʹͳ͍ͬͯ
    Δɻ
    • ม׵͸func _bridgeAnythingToObjectiveC(_ x: T) ->
    AnyObjectͰߦΘΕ͍ͯΔɻ
    13
    

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16. public func _bridgeAnythingToObjectiveC(_ x: T) -> AnyObject {
    var done = false
    var result: AnyObject!
    let source: Any = x
    if let dynamicSource = _extractDynamicValue(x) {
    result = dynamicSource as AnyObjectɹ// ← ʂʂʂ
    done = true
    }
    14
    

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17. if !done, let wrapper = source as? _Unwrappable {
    if let value = wrapper._unwrap() {
    result = value as AnyObjectɹ// ← ʂʂʂ
    } else {
    result = _nullPlaceholder
    }
    done = true
    }
    15
    

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18. if !done {
    if type(of: source) as? AnyClass != nil {
    result = unsafeBitCast(x, to: AnyObject.self) // ↓ʂʂʂ
    } else if let object = _bridgeToObjectiveCUsingProtocolIfPossible(source) {
    result = object
    } else {
    result = _makeSwiftValue(source) // ← ʂʂʂ
    }
    }
    return result
    }
    16
    

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19. SwiftͱObjective-Cͷܕͷ૬ޓม׵
    17
    

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20. SwiftͱObjective-Cͷܕͷ૬ޓม׵
    • func _bridgeAnythingToObjectiveC(_ x: T) -> AnyObjectͷத
    ͰObjective-Cͷܕʹม׵΍__SwiftValue΁ͷϥοϓ͕ߦΘΕͯ
    ͍Δɻ
    17
    

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21. __SwiftValueͱ͸
    // __SwiftValue is an Objective-C class, but we shouldn't interface with it
    // directly as such. Keep the type opaque.
    #if __OBJC__
    @class __SwiftValue;
    #else
    typedef struct __SwiftValue __SwiftValue;
    #endif
    swift/stdlib/public/runtime/SwiftValue.h
    18
    

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22. __SwiftValueͱ͸
    // __SwiftValue is an Objective-C class, but we shouldn't interface with it
    // directly as such. Keep the type opaque.
    #if __OBJC__
    @class __SwiftValue;
    #else
    typedef struct __SwiftValue __SwiftValue;
    #endif
    swift/stdlib/public/runtime/SwiftValue.h
    • Objective-Cͷclass
    18
    

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23. ໰୊4
    /* Objective-C */
    @interface ObjCModel : NSObject
    - (NSString *)test:(id)any;
    @end
    @implementation ObjCModel
    - (NSString *)test:(id)any {
    return NSStringFromClass([any class]);
    }
    @end
    19
    

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24. ໰୊4
    /* Swift */
    class ObjCModel : NSObject {
    func test(_ any: Any!) -> String!
    }
    20
    

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25. ໰୊4
    let objcModel = ObjCModel()
    type(of: objcModel) // ObjCModel
    objcModel.test(StructModel()) // ԿʹͳΔʁ
    21
    

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26. ౴͑4
    let objcModel = ObjCModel()
    type(of: objcModel) // ObjCModel
    objcModel.test(StructModel()) // __SwiftValue
    __SwiftValue
    22
    

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27. Anyͳͷʹʁ
    !
    23
    

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28. SwiftͰͷas Anyͷڍಈ
    let structModel = StructModel()
    type(of: structModel as Any) // StructModel
    24
    

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29. SwiftͰͷidܕͷѻ͍
    Objective-C Swift 2 Swift 3
    id AnyObject Any
    NSArray * [AnyObject] [Any]
    NSDictionary * [NSObject: AnyObject] [AnyHashable: Any]
    NSSet * Set Set
    Ҿ༻ݩ: Objective-C id as Swift Any 25
    

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30. SwiftͰͷidܕͷѻ͍
    Objective-C Swift 2 Swift 3
    id AnyObject Any
    26
    

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31. SwiftͰͷidܕͷѻ͍
    Objective-C Swift 2 Swift 3
    id AnyObject Any
    • Swift 2Ͱ͸ idܕ͸AnyObjectܕͱͯ͠ѻΘΕ͍ͯͨɻ
    26
    

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32. SwiftͰͷidܕͷѻ͍
    Objective-C Swift 2 Swift 3
    id AnyObject Any
    • Swift 2Ͱ͸ idܕ͸AnyObjectܕͱͯ͠ѻΘΕ͍ͯͨɻ
    • ͨͩ͠ɺAnyObjectͩͱSwiftͷstruct΍enum͕౉ͤͳ͍ෆ౎߹
    ͕͋ͬͨͨΊɺSwift 3͔ΒAnyܕʹมΘͬͨɻ
    26
    

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33. SwiftͰͷidܕͷѻ͍
    Objective-C Swift 2 Swift 3
    id AnyObject Any
    27
    

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34. SwiftͰͷidܕͷѻ͍
    Objective-C Swift 2 Swift 3
    id AnyObject Any
    • ͭ·ΓObjective-CͰ͸ݩʑAnyObjectʢࢀরܕʣ͔͠૝ఆͯ͠
    ͍ͳ͔͕ͬͨɺSwiftͷ஋ܕʢstruct, enumʣΛ౉ͤΔΑ͏ʹ͢
    ΔͨΊʹAnyܕʹมߋ͞Εɺ಺෦ͰରԠ͢Δclassܕʹม׵·ͨ
    ͸ϥοϓ͢Δ͜ͱʹͳͬͨɻ
    27
    

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35. SwiftͰͷidܕͷѻ͍
    Objective-C Swift 2 Swift 3
    id AnyObject Any
    28
    

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36. SwiftͰͷidܕͷѻ͍
    Objective-C Swift 2 Swift 3
    id AnyObject Any
    • Objective-CͷAnyܕʹ஋Λ౉͢ͱ as AnyObject ͱಉ͘͡ func
    _bridgeAnythingToObjectiveC(_ x: T) -> AnyObjectʹΑΔܕม
    ׵͕ߦΘΕΔ͜ͱʹͳΔɻ
    28
    

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37. ࣮ࡍʹૺ۰ͨ͠໰୊
    29
    

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38. ࣮ࡍʹૺ۰ͨ͠໰୊
    30
    

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39. ࣮ࡍʹૺ۰ͨ͠໰୊
    • Objective-CͰ࣮૷͞ΕͨAnyܕΛҾ਺ʹ͍࣋ͬͯΔؔ਺ʹର͠
    ͯSwiftͷStructΛ౉ͨ͠ΒɺಉҰͷΠϯελϯεΛ౉͍ͯ͠Δ
    ͷʹObjective-CଆͰ͸ຖճҟͳΔΠϯελϯε͕౉͞Ε͍ͯΔ
    ͱ͍͏൑ఆʹͳͬͯ͠·ͬͨɻ
    30
    

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40. ࣮ࡍʹૺ۰ͨ͠໰୊
    • Objective-CͰ࣮૷͞ΕͨAnyܕΛҾ਺ʹ͍࣋ͬͯΔؔ਺ʹର͠
    ͯSwiftͷStructΛ౉ͨ͠ΒɺಉҰͷΠϯελϯεΛ౉͍ͯ͠Δ
    ͷʹObjective-CଆͰ͸ຖճҟͳΔΠϯελϯε͕౉͞Ε͍ͯΔ
    ͱ͍͏൑ఆʹͳͬͯ͠·ͬͨɻ
    • ཧ༝͸ɺຖճ৽͍͠__SwiftValueʹϥοϓ͞Εͯ౉͞ΕΔͨ
    Ίɻ
    30
    

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41. ࣮ࡍʹૺ۰ͨ͠໰୊
    31
    

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42. ࣮ࡍʹૺ۰ͨ͠໰୊
    • ྫ͑͹ɺؔ਺಺ͰΠϯελϯεͷಉ஋൑ఆΛͨ͠ϩδοΫ͕࣮
    ૷͞Ε͍ͯΔ࣌ʹɺݺͼग़͠ݩ͸ಉҰͷstructΛ౉͍ͯ͠Δͭ΋
    ΓͰ΋ɺؔ਺಺Ͱ͸ҟͳΔΠϯελϯεͱ൑ఆ͞Εͯ͠·͏ͷ
    Ͱҙਤͨ͠ڍಈʹͳΒͳ͘ͳΔɻ
    31
    

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43. Πϯελϯε͕ҟͳΔ͜ͱΛݕূ
    @frozen struct ObjectIdentifier
    32
    

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44. Πϯελϯε͕ҟͳΔ͜ͱΛݕূ
    @frozen struct ObjectIdentifier
    • ObjectIdentifierΛ࢖ͬͯɺੜ੒͞ΕͨΠϯελϯεͷҰҙͷID
    Λग़ͯ͠ΈΔͱɺಉҰͷstructͷ͸ͣͳͷʹ as AnyObject ͷ౓
    ʹҧ͏IDʹͳΔ͜ͱ͕֬ೝͰ͖Δɻ
    32
    

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45. Πϯελϯε͕ҟͳΔ͜ͱΛݕূ
    struct StructModel {}
    let structModel = StructModel()
    Timer.scheduledTimer(
    withTimeInterval: 1,
    repeats: true
    ) { _ in // 1ඵ͝ͱʹΫϩʔδϟ͕࣮ߦ͞ΕΔ
    print("struct", ObjectIdentifier(structModel as AnyObject))
    }
    33
    

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46. /*
    ग़ྗ͞ΕΔϩά
    struct ObjectIdentifier(0x00006000005749c0)
    struct ObjectIdentifier(0x000060000055ef80)
    struct ObjectIdentifier(0x00006000005557c0)
    struct ObjectIdentifier(0x000060000055dba0)
    struct ObjectIdentifier(0x000060000055ef80)
    struct ObjectIdentifier(0x00006000005557c0)
    */
    34
    

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47. /*
    ग़ྗ͞ΕΔϩά
    struct ObjectIdentifier(0x00006000005749c0)
    struct ObjectIdentifier(0x000060000055ef80)
    struct ObjectIdentifier(0x00006000005557c0) // ಉ͡IDʂʂʂ
    struct ObjectIdentifier(0x000060000055dba0)
    struct ObjectIdentifier(0x000060000055ef80)
    struct ObjectIdentifier(0x00006000005557c0) // ಉ͡IDʂʂʂ
    */
    35
    

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48. ObjectIdentifier͸ɺղ์͞ΕͨաڈͷΠϯελϯεͱಉ
    ͡IDΛฦ͢͜ͱ͕͋Δ
    36
    

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49. ObjectIdentifier͸ɺղ์͞ΕͨաڈͷΠϯελϯεͱಉ
    ͡IDΛฦ͢͜ͱ͕͋Δ
    • ͜Ε͸ͨ·ͨ·ಉ͡ϝϞϦྖҬ͕࢖͍·Θ͞Εͨͱਪ࡯͞Ε
    Δɻ
    36
    

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50. ObjectIdentifier͸ɺղ์͞ΕͨաڈͷΠϯελϯεͱಉ
    ͡IDΛฦ͢͜ͱ͕͋Δ
    • ͜Ε͸ͨ·ͨ·ಉ͡ϝϞϦྖҬ͕࢖͍·Θ͞Εͨͱਪ࡯͞Ε
    Δɻ
    • ObjectIdentifierͷ࢓༷తʹ΋ੜଘதͷΠϯελϯεͷൺֱ
    ʢcomparisons during the lifetime of the instance.ʣΛ૝ఆͯ͠
    ͍ΔIDͳͷͰɺ͢Ͱʹղ์͞ΕͨΠϯελϯεͱಉ͡IDʹͳͬ
    ͯ͠·͏Մೳੑ͸͋ΔͱࢥΘΕΔɻ
    36
    

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51. ObjectIdentifier͕ಉ͡IDΛฦ͢͜ͱ͕͋Δ
    37
    

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52. ObjectIdentifier͕ಉ͡IDΛฦ͢͜ͱ͕͋Δ
    • ͜ͷڍಈ͕͋ͬͨͨΊɺ֘౰ͷObjectivce-Cͷؔ਺͕ҙਤ௨Γ
    ʹಈ͍ͨΓಈ͔ͳ͔ͬͨΓͯ͠ௐ͕ࠪ೉ߤͨ͠ɻ
    37
    

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53. ະղܾͳٙ໰
    38
    

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54. ະղܾͳٙ໰
    • AnyObjectͬͯͳΜͩΖ͏ʁ
    38
    

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55. ະղܾͳٙ໰
    • AnyObjectͬͯͳΜͩΖ͏ʁ
    • υΩϡϝϯτతʹ͸͢΂ͯͷΫϥε͕҉໧తʹ४ڌ͢Δ
    protocolͱهࡌ͞ΕͯΔ͕ɺఆٛΛݟΔͱ typealias
    AnyObject ʹͳ͍ͬͯΔɻ
    38
    

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56. ະղܾͳٙ໰
    • AnyObjectͬͯͳΜͩΖ͏ʁ
    • υΩϡϝϯτతʹ͸͢΂ͯͷΫϥε͕҉໧తʹ४ڌ͢Δ
    protocolͱهࡌ͞ΕͯΔ͕ɺఆٛΛݟΔͱ typealias
    AnyObject ʹͳ͍ͬͯΔɻ
    • ݕࡧ͢Δͱtypealias AnyObject = Builtin.AnyObject͕ώοτ͢
    Δɻ
    38
    

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57. ͝੩ௌ͋Γ͕ͱ͏
    ͍͟͝·ͨ͠ʂ
    QRίʔυ: Swiftͷas Any / AnyObjectͷ҉໧తͳܕม׵ʹ͍ͭͯ 39
    

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