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potatotips #85 iOS/Android։ൃTipsڞ༗ձ
2023/11/14 @Voicy
if ࣜͱ switch ࣜʹΑΔ
SwiftUI ͷϓϨϏϡʔΤϥʔରࡦ
ojun - DeNA Co., Ltd.
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ࣗݾհʢojunʣ
• name: ojun
• 2023৽ଔೖࣾ
• iOSΤϯδχΞ
@ojun_9
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Xcode 15 ରԠਐΜͰ͍·͔͢ʁ
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Xcode 15.0
Asset Catalogs / String Catalogs
PreviewϚΫϩ
Swift 5.9
ϒοΫϚʔΫػೳ
ɾෳͷݴޠػೳͷՃ
ɾσόοά࣌ʹมͷ༰Λग़ྗ͢ΔͨΊʹར༻͢ΔpίϚϯυͱpoίϚϯυ
ʹΑΔग़ྗ͕࣌ؒେ෯ʹॖ
ͦͷଞ͍Ζ͍Ζ
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Xcode 15.0
Asset Catalogs / String Catalogs
PreviewϚΫϩ
Swift 5.9
ϒοΫϚʔΫػೳ
ɾෳͷݴޠػೳͷՃ
ͦͷଞ͍Ζ͍Ζ
ɾσόοά࣌ʹมͷ༰Λग़ྗ͢ΔͨΊʹར༻ՄೳͳpίϚϯυͱpoίϚϯυ
ʹΑΔग़ྗ͕࣌ؒେ෯ʹॖ
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Swift 5.9: if ͱ switch ͷࣜදݱ
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Swift 5.9: ifͱswitchͷࣜදݱ
Swift 5.9͔ΒswitchͱifΛࣜͱͯ͠දݱͰ͖ΔΑ͏ʹͳͬͨ
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Swift 5.9: ifͱswitchͷࣜදݱ
Swift 5.9͔ΒswitchͱifΛࣜͱͯ͠දݱͰ͖ΔΑ͏ʹͳͬͨ
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Swift 5.9: ifͱswitchͷࣜදݱ
Swift 5.9͔ΒswitchͱifΛࣜͱͯ͠දݱͰ͖ΔΑ͏ʹͳͬͨ
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Swift 5.9: ifͱswitchͷࣜදݱ
Swift 5.9͔ΒswitchͱifΛࣜͱͯ͠දݱͰ͖ΔΑ͏ʹͳͬͨ
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Swift 5.9: ifͱswitchͷࣜදݱ
Swift 5.9͔ΒswitchͱifΛࣜͱͯ͠දݱͰ͖ΔΑ͏ʹͳͬͨ
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Preview࣌ʹར༻͢Δ
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Preview࣌ʹར༻͢Δ
isSwiftͷBoolʹج͍ͮͯTextΛฦ͢
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Preview࣌ʹར༻͢Δ
isSwiftͷBoolʹج͍ͮͯTextΛฦ͢
௨ৗͷϏϧυ
🎉 ͳ͘ޭ͢Δ
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Preview࣌ʹར༻͢Δ
isSwiftͷBoolʹج͍ͮͯTextΛฦ͢
௨ৗͷϏϧυ
🎉 ͳ͘ޭ͢Δ
Preview࣌ͷϏϧυ
😭 ίϯύΠϧΤϥʔ͕ൃੜ͢Δ
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Preview࣌ʹར༻͢Δ
isSwiftͷBoolʹج͍ͮͯTextΛฦ͢
௨ৗͷϏϧυ
🎉 ͳ͘ޭ͢Δ
Preview࣌ͷϏϧυ
😭 ίϯύΠϧΤϥʔ͕ൃੜ͢Δ
Preview ProviderΛར༻ͯ͠ಉ༷
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Preview࣌ʹར༻͢Δ
'if' may only be used as expression
in return, throw, or as the source
of an assignment
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ղܾํ๏
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ղܾํ๏
1. @ViewBuilderΩʔϫʔυΛ༩͢Δ
2. Opaque typeͰͳ͍໌֬ͳܕΛฦ͢
3. Opaque Type Λ Existential Type ʹஔ͖͑Δ
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@ViewBuilderΩʔϫʔυΛ༩͢Δ
@ViewBuilderΩʔϫʔυΛ༩͢Δ
͜ͱͰPreview࣌ͷΤϥʔΛճආͰ͖Δ
௨ৗͷϏϧυ
🎉 ͳ͘ޭ͢Δ
Preview࣌ͷϏϧυ
🎉 ͳ͘ޭ͢Δ
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໌֬ͳܕΛฦ͢
௨ৗͷϏϧυ
🎉 ͳ͘ޭ͢Δ
Preview࣌ͷϏϧυ
🎉 ͳ͘ޭ͢Δ
`Text`ͷΑ͏ʹܕΛ໌֬ʹ͢Δ
͜ͱͰPreview࣌ͷΤϥʔΛճආͰ͖Δ
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Opaque Type Λ Existential Type ʹஔ͖͑Δ
ΓΛany Viewʹ͢Δํ๏
ͨͩ͠ɺݺͼग़͠ݩͰܕΩϟετΛ
ߦ͏ඞཁ͕͋Δ
௨ৗͷϏϧυ
🎉 ͳ͘ޭ͢Δ
Preview࣌ͷϏϧυ
🎉 ͳ͘ޭ͢Δ
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ͷݪҼΛߟ͢Δ
ʢࠜຊݪҼಥ͖ࢭΊΒΕ·ͤΜͰͨ͠😢ʣ
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ͷݪҼΛߟ͢Δ
ContentView.1.preview-thunk.swift ͱ͍͏ϑΝΠϧ͕ҎԼʹଘࡏ͢Δ
~/Library/Developer/Xcode/DerivedData/MakeViewFromSwitch-
fghepcludbkyehbmhgmucvzdrxsk/Build/Intermediates.noindex/Previews/
MakeViewFromSwitch/Intermediates.noindex/MakeViewFromSwitch.build/
Debug-iphonesimulator/MakeViewFromSwitch.build/Objects-normal/arm64
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ContentViewͷPreviewϏϧυ͕Δͱ͜ͷϑΝΠϧ͕ߋ৽͞ΕΔ
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ྫ͑ɺany ErrorΛฦ͢Α͏ͳϝιουΛ࣮͢Δͱ
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ContentView.1.preview-thunk.swift ߋ৽͞ΕΔ
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ΓΛOpaque Typeʹ͢Δͱ
ͨͩ͠
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ContentView.1.preview-thunk.swift ͔ΒgetErrorͷॲཧ͕ফ͑Δ
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ͷݪҼΛߟ͢Δ
ίϯύΠϧΤϥʔʹͳ࣮ͬͨ
Opaque Typeͩͬͨ
తͳݪҼ͔Θ͔Βͳ͍͕͜Ε͕
ʹͳ͍ͬͯΔՄೳੑ͕͋Δ
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·ͱΊ
Swift 5.9͔Β if ͱ switch Λࣜͱͯ͠ѻ͑ΔΑ͏ʹͳͬͨ
if / switch ࣜΛ༻͍ͯSwiftUIͷViewΛʢopaque typeͱͯ͠ʣฦ͢ͱ
Preview࣌ͷϏϧυͰͷΈίϯύΠϧΤϥʔ͕ൃੜ͢Δ
ҎԼͷ͍ͣΕ͔ͷํ๏ͰͷରԠΛ͢Δ͜ͱ͕Ͱ͖Δ
1. @ViewBuilderΩʔϫʔυΛ༩͢Δ
2. Opaque typeͰͳ͍໌֬ͳܕΛฦ͢ʢText ͳͲʣ
3. Opaque Type Λ Existential Type ʹஔ͖͑Δ
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͋Γ͕ͱ͏͍͟͝·ͨ͠ʂ