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Property Wrapperͽ
Decodable΄ϔϢζϸϕ㮔Ψ戔ਧ
櫏JSONϹφϪЀφ揗͚ͧ
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Jierong Liҁ҂
• ໌ୗտᐒΜΗΕ
• iOSεЀυϘί
• h&ps:/
/jierong.dev
• ڡΗͼ晁㻑ιϐϑϷ݇ے
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Ξͥ͘ΡDecodable
enum Bar: String, Decodable {
case case1, case2
}
struct Foo: Decodable {
let array: [Int]
let string: String
let int: Int
let double: Double
let bar: Bar
}
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ϔϢζϸϕ㮔戔ਧ
enum Bar: String, Decodable {
case case1, case2
}
struct Foo: Decodable {
let array: [Int]
let string: String
let int: Int
let double: Double
let bar: Bar
private enum CodingKeys: CodingKey {
case array, string, int, double, bar
}
init(from decoder: Decoder) throws {
let container = decoder.container(keyedBy: CodingKeys.self)
array = decoder.decodeIfPresent([Int].self, forKey: .array) ?? []
string = decoder.decodeIfPresent(String.self, forKey: .string) ?? ""
int = decoder.decodeIfPresent(Int.self, forKey: .int) ?? 0
double = decoder.decodeIfPresent(Double.self, forKey: .double) ?? -1
bar = decoder.decodeIfPresent(Bar.self, forKey: .bar) ?? .case2
}
}
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᭗ଉαϘτϰ϶ασЄ
enum Bar: String, Decodable {
case case1, case2
}
struct Foo: Decodable {
let array: [Int]
let string: String
let int: Int
let double: Double
let bar: Bar
private enum CodingKeys: CodingKey {
case array, string, int, double, bar
}
init(from decoder: Decoder) throws {
let container = decoder.container(keyedBy: CodingKeys.self)
array = decoder.decodeIfPresent([Int].self, forKey: .array) ?? []
string = decoder.decodeIfPresent(String.self, forKey: .string) ?? ""
int = decoder.decodeIfPresent(Int.self, forKey: .int) ?? 0
double = decoder.decodeIfPresent(Double.self, forKey: .double) ?? -1
bar = decoder.decodeIfPresent(Bar.self, forKey: .bar) ?? .case2
}
init(array: [Int] = [], string: String = "", int: Int = 0, double: Double = -1, bar: Bar = .case2) {
self.array = array
self.string = string
self.int = int
self.double = double
self.bar = bar
}
}
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ϔϢζϸϕ㮔͢ӞͺͶͧͽΘ
enum Bar: String, Decodable {
case case1, case2
}
struct Foo: Decodable {
let array: [Int]
let string: String
let int: Int
let double: Double
let bar: Bar
private enum CodingKeys: CodingKey {
case array, string, int, double, bar
}
init(from decoder: Decoder) throws {
let container = decoder.container(keyedBy: CodingKeys.self)
array = decoder.decodeIfPresent([Int].self, forKey: .array) ?? []
string = decoder.decode(String.self, forKey: .string)
int = decoder.decode(Int.self, forKey: .int)
double = decoder.decode(Double.self, forKey: .double)
bar = decoder.decode(Bar.self, forKey: .bar)
}
init(array: [Int] = [], string: String, int: Int, double: Double, bar: Bar) {
self.array = array
self.string = string
self.int = int
self.double = double
self.bar = bar
}
}
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晄౮ͭ͵͚ͩ;
• Property WrapperͽϔϢζϸϕ㮔΄戔ਧ
• ݶͮόαϤ䌏ͭͼ晅͜ϔϢζϸϕ㮔΄戔ਧ
• όαϤࢴํϔϢζϸϕ㮔΄戔ਧ
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ݶͮόαϤ䌏ͭͼ晅͜ϔϢζϸϕ㮔΄戔ਧ
struct Foo: Decodable {
@DefaultBy([]) var array: [Int]
}
Decodable΄ᇙΞͼ
!
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υδϚϷμφͽ䌏㳌
protocol Default {
associatedtype Value
static var defaultValue: Value { get }
}
@propertyWrapper
struct DefaultDecodable: Decodable where D.Value: Decodable {
let wrappedValue: D.Value
init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
wrappedValue = try container.decode(D.Value.self)
}
init() {
wrappedValue = D.defaultValue
}
}
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ExtensionͽηЄϝЄϺЄϖ
extension KeyedDecodingContainer {
func decode(_ type: DefaultDecodable.Type,
forKey key: Key) throws -> DefaultDecodable {
try decodeIfPresent(type, forKey: key) ?? .init()
}
}
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ᑮ
protocol EmptyInitializable {
init()
}
struct EmptyDefault: Default {
static var defaultValue: Value { .init() }
}
extension Array: EmptyInitializable {}
extension String: EmptyInitializable {}
struct Foo: Decodable {
@DefaultDecodable var array: [Int]
@DefaultDecodable var string: String
...
}
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ෆቘ
enum CommonDefault {
struct Empty: Default {
static var defaultValue: Value { .init() }
}
}
enum DefaultBy {
typealias Empty
= DefaultDecodable>
}
struct Foo: Decodable {
@DefaultBy.Empty var array: [Int]
@DefaultBy.Empty var string: String
...
}
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හ㮔
enum CommonDefault {
...
struct ZeroInt: Default {
static var defaultValue: Int {̴.zero̴}
}
struct OneInt: Default {
static var defaultValue: Int { 1 }
}
struct MinusOneInt: Default {
static var defaultValue: Int { -1 }
}
struct ZeroDouble: Default {
static var defaultValue: Double {̴.zero̴}
}
struct OneDouble: Default {
static var defaultValue: Double { 1 }
}
struct MinusOneDouble: Default {
static var defaultValue: Double { -1 }
}
...
}
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හ㮔
enum CommonDefault {
...
struct Zero: Default {
static var defaultValue: Value {̴.zero̴}
}
struct One: Default {
static var defaultValue: Value { 1 }
}
struct MinusOne: Default {
static var defaultValue: Value { -1 }
}
}
enum DefaultBy {
...
typealias Zero = DefaultDecodable>
typealias One = DefaultDecodable>
typealias MinusOne = DefaultDecodable>
}
struct Foo: Decodable {
...
@DefaultBy.Zero var int: Int
@DefaultBy.MinusOne var double: Double
...
}
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όαϤࢴํ
protocol SelfDefault: Default {
static var defaultValue: Self { get }
}
extension Bar: SelfDefault {
var defaultValue: Bar { .case2 }
}
enum DefaultBy {
...
typealias `Self` = DefaultDecodable
}
ςϣμ϶φͽΘSelf΄ګ夹͢伋͵ͱΡ͵Η̵ࣳവ抷͢ӧݢᚆ
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όαϤࢴํ
protocol SelfDefault {
static var defaultValue: Self { get }
}
enum CommonDefault {
...
struct `Self`: Default {
static var defaultValue: Value { Value.defaultValue }
}
}
enum DefaultBy {
...
typealias `Self` = DefaultDecodable>
}
struct Foo: Decodable {
...
@DefaultBy.Self var bar: Bar
}
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๋奰奾ຎ
struct Foo: Decodable {
@DefaultBy.Empty var array: [Int]
@DefaultBy.Empty var string: String
@DefaultBy.Zero var int: Int
@DefaultBy.MinusOne var double: Double
@DefaultBy.Self var bar: Bar
}
φϐκϷͭ͵̵ͭ᭗ଉαϘτϰ϶ασЄΘκЄϤ
h"ps:/
/github.com/myihsan/DefaultDecodableWrapper
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ΚΟͭ͡͵ͩ;
extension DefaultDecodable: Equatable where D.Value: Equatable {}
extension DefaultDecodable: Encodable where D.Value: Encodable {}
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ΚΟͭ͡͵ͩ;
extension DefaultDecodable: Equatable where D.Value: Equatable {}
// extension DefaultDecodable: Encodable where D.Value: Encodable {}̴
// { "wrappedValue": 1 }
extension DefaultDecodable: Encodable where D.Value: Encodable {
public func encode(to encoder: Encoder) throws {
var container = encoder.singleValueContainer()
try container.encode(wrappedValue)
}
}
ϓφϕώЄϭ;ץྋͭ͵ϮЀϝЄఽ拽
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ͪᶉ宛͘Π͢;͚ͪͬ͜Δͯ