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ࠓ͔Β͑Δʂ
OptionalΛ͍͍ײ͡ʹѻ͏tips
2019/3/19 ͋Δ͋ΔLTʙεϚϗΞϓϦ։ൃΤϯδχΞʙ Vol.3
PKPK-Carnage(Tomosuke Okada)
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About me
• iOSྺ2ͪΐͬͱ
• Qiita → @PKPK-Carnage
• Github → PKPK-Carnage
• Twitter → @PKPK-Carnage
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࠷ۙࢥͬͨ͜ͱɾɾɾ
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OptionalΛ੍͢ΔऀSwiftΛ੍͢!!
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tips1: switch
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switch
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enum TestType: Int {
case hoge = 0
case fuga = 1
case piyo = 2
}
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switch
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func generateText(from index: Int) -> String {
guard let unwrappedType = TestType(rawValue: index) else {
return ""
}
switch unwrappedType {
case .hoge:
return "Hoge"
case .fuga:
return "Fuga"
case .piyo:
return "Piyo"
}
}
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case?ͱ.noneΛ͏ͱɾɾɾ
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switch
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func generateText(from index: Int) -> String {
guard let unwrappedType = TestType(rawValue: index) else {
return ""
}
switch unwrappedType {
case .hoge:
return "Hoge"
case .fuga:
return "Fuga"
case .piyo:
return "Piyo"
}
}
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switch
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func generateText(from index: Int) -> String {
switch TestType(rawValue: index) {
case .hoge?:
return "Hoge"
case .fuga?:
return "Fuga"
case .piyo?:
return "Piyo"
case .none:
return ""
}
}
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switchͷఆର͕nilͩͬͨ߹ͷॲཧΛ
.noneʹهड़Ͱ͖Δʂ
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tips2: Nil Coalescing Operator + Closure
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Nil Coalescing Operator
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let text = ""
let intValue = Int(text) == nil ? 0 : Int(text)!
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Nil Coalescing Operator
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let text = ""
let intValue = Int(text) ?? 0
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ཁ͢Δʹࡾ߲ԋࢉࢠͷলུ
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??ͷޙʹClosureࢦఆͰ͖Δ
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Nil Coalescing Operator
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let text = ""
let intValue = Int(text) ?? 0
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Nil Coalescing Operator + Closure
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let text = ""
let intValue = Int(text) ?? { return 0 }()
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͜ΕͰ͖ͯԿʹͳΔͷʁ
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׆༻๏
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let text = ""
let intValue = Int(text) ?? { return 0 }()
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׆༻๏
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let text = ""
let intValue = Int(text) ?? {
assertionFailure("ࣈͷςΩετ͕ೖͬͯ·ͤΜʂ")
return 0
}()
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σόοάϏϧυͷ͚࣌ͩnilͩͬͨ࣌ʹ
Ϋϥογϡͤ͞ΒΕΔ
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·ͱΊ
• optionalͷΦϒδΣΫτΛswitchʹ͢Δͱ͖ɺcase?
ͱ.noneΛ͏ͱΞϯϥοϓ͢Δඞཁ͕ͳ͍
• ??ͷޙʹClosureΛೖΕΔ͜ͱ͕Ͱ͖ΔͷͰɺ͔ͳΓࣗ༝
͕ߴ͍ɻ
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͓ΘΓ
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