Swift のイニシャライザーの基礎的なところについて 30 分くらいで復習するのに使った資料です。2017/03/06 の『AKIBA.swift × Swift愛好会 vol2』で発表しました。

7. struct Person {
init(name: String, number: Int) {
}
}

8. struct Person {
var name: String
var number: Int
init(name: String, number: Int) {
self.name = name
}
}

10. struct Person {
init(name: String, number: Int) {
guard name.isVaidAsPersionName() else {
fatalError("Invalid name")
}
:

11. init? init!
nil
struct Person {
init?(name: String, number: Int) {
guard name.isVaidAsPersionName() else {
return nil
}
:

12. init … throws
struct Person {
init(name: String, number: Int) throws {
guard name.isVaidAsPersionName() else {
throw InitializeError.invalidName
}
:

13. class Person {
var name: String
var number: Int
init?(name: String, number: Int) {
guard name.isVaidAsPersionName() else {
return nil
}

15. struct Person {
init(name: String, number: Int) {
}
init(havingName: String, andNumber: Int) {
}

16. struct Number {
init( _ string: String, radix: Int) {
}

17. struct WebSite {
init(url: String, baseAddress: URL? = nil) {
}

20. struct Person {
var name: String
var number: Int
init(name: String) {
self.name = name
self.number = getNextNumber()
}

21. struct Person {
var name: String
var number: Int
}
// イニシャライザーを定義しなくても使える
let someone = Person(name: "Kumagai", number: 2)

22. struct Person {
var name: String
var number: Int
}
extension Person {
init(name: String) {
self.init(name: name, number: getNextNumber())
}

24. class Base {
init(name: String, number: Int) {
}
}

25. class Base {
convenience init(name: String) {
self.init(name: name, number: getNextNumber())
}
}

26. class Base {
required init(name: String, number: Int) {
}
}

27. extension Object {
convenience init(a: Int) { … }
init(b: Int) { … }
required nit(c: Int) { … }

29. class View {
var textColor = NSColor.black
var backgroundColor = NSColor.white
init() {
}
}

30. class Object {
var value = Value()
init() {
value = Value()
}
}

31. struct Data {
var value = Value()
}
let data = Data(value: Value())

33. struct Person {
var name: String
var number: Int
init(name: String) {
self.name = name
self.number = getNextNumber()
}
}

34. struct Person {
var name: String
var number: Int
}
extension Persion {
init(name: String) {
self.name = name
self.number = getNextNumber()
}

35. struct RandomGenerator {
var seed1: UInt32 = arc4random()
var seed2: UInt32 = arc4random()
}
let gen1 = RandomGenerator()
let gen2 = RandomGenerator(seed1: 0, seed2: 1)

38. public struct MyData {
public var value = MyValue()
public init(value: MyValue) {
self.value = value
}
}

39. public struct MyData {
public var value = MyValue()
}
extension MyData {
public init(memberwiseWithValue value: MyValue) {
self.init(value: value)
}
}

40. public struct MyData {
public var value: MyValue
public init(value: MyValue) {
self.value = value
}
}

42. let speaker = Person("Kumagai", 1234)

43. let h = Person.init(name: "Kumagai", number: 1234)
// 関数型変数 f にイニシャライザーを入れて使える
let f: (String,Int) -> Person
= Person.init(name:number:)
let someone = f("Kumagai", 1234)

44. // 取り得る型から推論する
let list = MemberList(persons: .init(name: "A"))
// 関数内で、戻り値の型から推論する
func makePerson(name: String) -> Person {
return .init(name: name)
}

46. protocol ExpressibleByName {
init(name: String)
}

47. // 値型をプロトコルに適合させるとき
struct Person : ExpressibleByName {
init(name: String) { … }
}
// 参照型をプロトコルに適合させるとき
class Thread : ExpressibleByName {
required init(name: String) { … }
}

48. // 値型はプロトコルに適合できる
extension Person : ExpressibleByName {
init(name: String) { … }
}
// 参照型はプロトコルに適合できない
extension Thread : ExpressibleByName {
required init(name: String) { … }
}

50. struct Value {
init() { … }
}
// メタタイプ型の変数に保存して …
let type: Value.Type = Value.self
// そこからインスタンスを生成できる
let instance: Value = type.init()
型.self
init

51. class Object {
required init(a: Int) {}
init(b: Int) {}
}
let type: Object.Type = Object.self
let a = type.init(a: 0)
let b = type.init(b: 0)

52. class Base {
required init() { … }
}
class Sub : Base {
required init() { … }
}
let types = [Base.self, Sub.self] as [Base.Type]
let instances = types.map { $0.init() }