29. Optional<T>をValueTypeで拡張
public protocol ValueType {
static func fromJSON(json: AnyObject?) -> Self?
func toJSON() -> AnyObject?
}
extension Optional: ValueType {
public static func fromJSON(json: AnyObject?) -> Wrapped?? {
guard let valueType = Wrapped.self as? ValueType.Type,
let value = valueType.fromJSON(json),
let wrapped = value as? Wrapped else {
return .Some(.None)
}
return .Some(.Some(wrapped))
}
public func toJSON() -> AnyObject? {
switch self {
case .Some(let wrapped):
guard let value = wrapped as? ValueType else {
return nil
}
return value.toJSON()
case .None:
return nil
}
}
}
30. どういうこと？
static func fromJSON
let optionalInt = Int?.fromJSON(json: 1)
print(optionalInt) // -> Optional<Optional(1)>
if let unwrappedOptinalInt = optionalInt {
print(unwrappedOptionalInt) // -> Optional(1)
}
?上記のコードはOptional<Int>へのスタティックメソッド呼び出し
?fromJSONはSelf?を返すので、optionalIntの型はOptional<Optional<Int>>になる
func toJSON（instance func）
let json = optionalInt.toJSON()
?Optional<Int>に追加されたtoJSONを呼び出している
31. Propertyクラスで行われていること
public class Property<Value: ValueType>: PropertyType {
public var value: Value
public func fromJSON(json: AnyObject) {
// ...NSNullの処理
if let value = Value.fromJSON(json) { // <- ここ
self.value = value
}
}
public func toJSON() -> AnyObject? {
if let json = value.toJSON() {
return json
}
// ...NSNullの処理
return nil
}
}
![Kaisekiを使うとこうなる
こんなオブジェクトを宣言
class Object: Entity {
// Basic
let int = Property<Int>()
let string = Property<String>()
// Array
let array = Property<[Bool]>()
// Optional
let optional = Property<Int?>()
// Entity
let object = Property<Object?>()
}
使い方
let json: [String: AnyObject] = [“int”: 1, “string”: “aaa”, “array”: [true, false], “optional”: null, ....]
let obj = Object.fromJSON(json: jsonData)
obj.int.value // -> 1
obj.string.value // -> aaa](https://image.slidesharecdn.com/0osplzdjtq6ad3ygdvss-signature-d21dcfefd6d33f53ae02b1e096362d1e978b4bd7df8f88b08917f57c4e451811-poli-160125100416/85/Deep-dive-into-oss-written-in-swift-20-320.jpg)
![Entityクラス
public class Entity: ValueType {
typealias ReflectedProperty = (label: String, property: PropertyType)
private lazy var reflectedProperties: [ReflectedProperty] = {
return Mirror(reflecting: self).children.filter { $1 is PropertyType }.flatMap {($0!, $1 as! PropertyType)}
}()
public static func fromJSON(json: AnyObject?) -> Self? {
// …
reflectedProperties.forEach {
let key = $1.keyWith($0)
if let value = dic[key] {
$1.fromJSON(value)
}
}
}
}](https://image.slidesharecdn.com/0osplzdjtq6ad3ygdvss-signature-d21dcfefd6d33f53ae02b1e096362d1e978b4bd7df8f88b08917f57c4e451811-poli-160125100416/85/Deep-dive-into-oss-written-in-swift-24-320.jpg)
![今一度サンプルコードを見てみる
こんなオブジェクトを宣言
class Object: Entity {
// Basic
let int = Property<Int>()
let string = Property<String>()
// Array
let array = Property<[Bool]>()
// Optional
let optional = Property<Int?>()
// Entity
let object = Property<Object?>()
}
使い方
let json: [String: AnyObject] = [“int”: 1, “string”: “aaa”, “array”: [true, false], “optional”: null, ....]
let obj = Object.fromJSON(json: jsonData)
obj.int.value // -> 1
obj.string.value // -> aaa](https://image.slidesharecdn.com/0osplzdjtq6ad3ygdvss-signature-d21dcfefd6d33f53ae02b1e096362d1e978b4bd7df8f88b08917f57c4e451811-poli-160125100416/85/Deep-dive-into-oss-written-in-swift-27-320.jpg)
