SwiftUIむけに整理された状態監視 Observation

4XJGU6*Ή͚ʹ ੔ཧ͞Εͨঢ়ଶ؂ࢹ 0CTFSWBUJPO ೳొཁ !OPUPSPJE J1IPOFΞϓϦ։ൃऀ೥݄೔

࠷ۙͷ׆ಈ 4XJGU6*Λཧղ͢ΔͨΊʹ4XJGUݴޠͷڍಈʹ͍ͭͯ࿩͢͜ͱ͕ଟ͠ w Αͤ͋ͭΊ4XJGU4XJGU4QFBLFS%FDL w IUUQTTQFBLFSEFDLDPNOPUPSPJEZPTFBUVNFTXJGUTXJGUEPU w "QQMF͕ ΍Γ͍ͨ์୊4XJGU"UUSJCVUFT4QFBLFS%FDL w
IUUQTTQFBLFSEFDLDPNOPUPSPJEBQQMFHBZBSJUBJGBOHUJTXJGU BUUSJCVUFT w 4XJGU6*͕؆ܿʹهड़Ͱ͖ΔΑ͏ʹͳΔ΄Ͳ4XJGUݴޠͱัଊػೳ͕ෳࡶԽ ͍ͯ͠Δ

࿩͢಺༰ w 4PVSDFPGUSVUI w $PNCJOFͱ0CTFSWBUJPOͷهड़ํ๏ൺֱ w 0CTFSWBUJPOͷૂ͍ w 0CTFSWBUJPOΛ࣮ݱՄೳͱ͍ͯ͠Δٕज़

࿩͞ͳ͍಺༰ w σʔλόΠϯσΟϯά !#JOEJOH w $PNCJOFͱ0CTFSWBUJPOͷ૬ޓӡ༻ w 0CTFSWBUJPOͷखಈ࣮૷

͓୊໨ w 4XJGU6*प೥ w هड़ํ๏ൺֱ$PNCJOFͱ0CTFSWBUJPO w 0CTFSWBUJPOͷૂ͍ w ·ͱΊ

4XJGU6*प೥

4XJGU6*प೥ ϚϧνϓϥοτϑΥʔϜରԠͷ6*ϑϨʔϜϫʔΫ w 6*पΓͷॆ࣮ "OJNBUJPO 8JEHFU w 4XJGU6*Λࢧ͑Δ࢓૊ΈͰ͋Δঢ়ଶ؂ࢹʹ͍ͭͯେ͖ͳΞοϓσʔτ w
ʙ$PNCJOFGSBNFXPSLΛ࢖ͬͨঢ়ଶ؂ࢹΛ4XJGU6*ͱ૊Έ߹Θͤ w </FX>ʙ0CTFSWBUJPOGSBNFXPSLΛ࢖ͬͨঢ়ଶ؂ࢹͱ૊Έ߹ΘͤΔ

0CTFSWBUJPOGSBNFXPSL "QQMFۘ੡σʔλ؍ଌϑϨʔϜϫʔΫ w J04Ҏ߱ରԠ w ։ൃπʔϧ9DPEFҎ߱ w $PNCJOFGSBNFXPSL ʙ ͷ୅ΘΓʹ4XJGU6*Ͱར༻Ͱ͖Δ
w 4XJGUιʔείʔυ্ͰJNQPSU0CTFSWBUJPOͰએݴ͢Δ͜ͱͰ࢖༻Մೳ

%JTDPWFS 0CTFSWBUJPOJO 4XJGU6* IUUQTEFWFMPQFSBQQMFDPN XXED

೔ຊޠʹ༁ͨ͠༗ࢤͷํ ʲ88%$ʳ%JTDPWFS0CTFSWBUJPOJO 4XJGU6*ʢ೔ຊޠ༁ʣ IUUQTCMPHDPEFDBOEZDPN EJTDPWFS@PCTFSWBUJPO@JO@TXJGUVJ

େ·͔ͳ಺༰ %JTDPWFS0CTFSWBUJPOJO4XJGU6*

0CTFSWBUJPO GSBNFXPSLͰ͜Ε· Ͱͷํ๏ΑΓ΋࢖͍΍ ͘͢ͳͬͨͥɺώϟο ϋʔʂ ৽ػೳਪ͠ͰϝϦοτ͕͸͖ͬΓ͠ͳ͍ɻ

ଞͷهࣄ΋ݟͯΈΔ

88%$ޙͷ#MPHهࣄ ͞Α͏ͳΒɺ$PNCJOFɻͦͯ͜͠Μʹͪ͸ɺ0CTFSWBUJPOɻ2JJUB IUUQTRJJUBDPNMPWFFJUFNTECCBCCD େ·͔ͳ಺༰ ͜Ε·Ͱͷ࢓૊Έ $PNCJOFGSBNFXPSL ͸4XJGU6*͕ඞཁͱͯ͠ ͍Δঢ়ଶ؂ࢹʹ͸༨ܭͳ΋ͷ͕ଟ͗ͨ͢ɻ 4XJGU6*ʹඞཁͳঢ়ଶ؂ࢹ͚ͩΛఏڙͨ͠ͷ͕0CTFSWBUJPOͳͷͰ ࠓޙ͸0CTFSWBUJPOΛ࢖͍ͬͯ͜͏ɻ

ͳͥ0CTFSWBUJPO ໌֬ͳར఺΍ࠓޙͷల๬͕ظ଴Ͱ͖ͳ͍ݶΓɺ৽ϑϨʔϜϫʔΫΛ ಋೖ͢Δಈػͱͯ͠͸ෆ଍ͯ͠͸͍ͳ͍͔ ৽͍ٕ͠ज़ΛਐΊΔͳΒ͹ཧ٧Ίͷ෦෼͕΋͏ͪΐͬͱཉ͍͠

0CTFSWBUJPOʹؔ܎͢Δηογϣϯ 0CTFSWBUJPOͷઆ໌͸4XJGUͷ৽ػೳ 88%$ ͷதͰ4XJGUNBDSPT ͷઆ໌ʹؚ·Ε͍ͯΔ ˠ4XJGU6*͕0CTFSWBUJPOΛಋೖ͢Δར఺ʹ͍ͭͯ͸໌֬ʹ͸ޠΒΕ ͍ͯͳ͍ɻ IUUQTEFWFMPQFSBQQMFDPNXXED UJNF

$PNCJOFͱ0CTFSWBUJPO ৽چҧ͍Λߟ͑Δʹ͸Ͳ͏͢Ε͹ྑ͍͔

ͳΒ͹ಉ͡ػೳΛ αϯϓϧίʔυͰ֬ೝͯ͠ΈΑ͏

هड़ํ๏ൺֱ $PNCJOFͱ0CTFSWBUJPO

αϯϓϧίʔυ J04ʙ 0CTFSWBUJPO$PNCJOF$PEF$PNQBSJTPO HJUIVCDPNOPUPSPJE 0CTFSWBUJPO$PNCJOF$PEF$PNQBSJTPO

αϯϓϧίʔυΛݟΔલʹ 4XJGU6*ͷ͓໿ଋΛ֬ೝ HJUIVCDPNOPUPSPJE 0CTFSWBUJPO$PNCJOF$PEF$PNQBSJTPO

%BUB'MPX 5ISPVHI4XJGU6* 88%$ EFWFMPQFSBQQMFDPN WJEFPTQMBZ XXED UJNF

4XJGU6*Ͱͷσʔλهड़Օॴίϯηϓτ

ᶃσʔλιʔεΛ഑ஔ͢Δ7JFX ᶄσʔλιʔε 4XJGU6*Ͱͷσʔλهड़Օॴίϯηϓτ ᶅσʔλιʔεΛ؍ଌ͢Δ7JFX

ᶃσʔλιʔεΛ഑ஔ͢Δ7JFX ᶄσʔλιʔε͸ ΦϒδΣΫτதͷଐੑΛ؍ଌͤ͞ Δɻ 4XJGU6*Ͱͷσʔλهड़Օॴ ᶅσʔλιʔεΛ؍ଌ͢Δ7JFX

ᶃσʔλιʔεΛ഑ஔ͢Δ"QQ 4XJGU6*୯ମͰΞϓϦΛ࡞੒Ͱ ͖ΔΑ͏ʹͳͬͨͨΊ ᶄσʔλιʔε͸ ΦϒδΣΫτதͷଐੑΛ؍ଌͤ͞ Δɻ 4XJGU6*Ͱͷσʔλهड़Օॴ ᶅσʔλιʔεΛ؍ଌ͢Δ7JFX

4XJGU6*Ͱ͸؍ଌ͢Δ؍ଌՄೳͳ σʔλΦϒδΣΫτͷ ࢀরํ๏͕େ·͔ʹͭ

؍ଌՄೳͳσʔλͷࢀরํ๏ ύϥϝʔλʔ౉͠ ؀ڥม਺౉͠ 7JFXͷม਺ͱͯ͠࢖͏

؍ଌՄೳͳσʔλͷࢀরํ๏ύϥϝʔλʔ౉͠

؍ଌՄೳͳσʔλͷࢀরํ๏؀ڥม਺౉͠

؍ଌՄೳͳσʔλͷࢀরํ๏7JFXͷม਺ͱͯ͠࢖͏

λάฤूΞϓϦ w 5BHͷू߹Λ؅ཧ͢ΔΞϓϦ w 5BHʹ͸࿈൪Λ͚ͭΔ w 0CTFSWBUJPO$PNCJOFͷಉ͡ί ʔυΛهड़ w ؍ଌ͢ΔΦϒδΣΫτͷ౉͠ํ
΋छ༻ҙ αϯϓϧίʔυ

B λά5BH import Foundation struct Tag: Identifiable { let name:
String let value: Int var id: Int { value } } extension Array<Tag> { static func defaultTags() -> [Tag] { [.init(name: "Tag1", value: 1), .init(name: "Tag2", value: 2), .init(name: "Tag3", value: 3)] } } ᶃ*EFOUJ fi BCMFϓϩτίϧΛࢦఆ ᶄ഑ྻॳظԽ༻ͷTUBUJDؔ਺

C 7JFXͷॲཧ struct ContentViewByObservationDependOnViewLifecycle: View { var tagCollection: TagCollectionByObservation =
.init() var body: some View { VStack { Button { let newTagValue = tagCollection.collectionCount + 1 tagCollection.collection.append( .init(name: "Tag\(newTagValue)", value: newTagValue) ) } label: { Text("Add") } Text("Tag number:\(tagCollection.collectionCount)") List(tagCollection.collection) { tag in Label( title: { Text("\(tag.name)") }, icon: { Image(systemName: "tag.fill") } ) } .listStyle(.plain) } .padding() } } ᶃ7JFXͰ͸એݴʹҧ͍͋Γ ᶄϘλϯΛλοϓ͢Δͱ 5BH͕૿͑Δ͚ͩ

D σʔλιʔεΛ഑ஔ͢Δ"QQ import SwiftUI @main struct ObservationCombineCodeComparisonApp: App { @StateObject
var tagCollectionByCombine: TagCollectionByCombine = .init() var tagCollectionByObservation:TagCollectionByObservation = .init() var body: some Scene { … } } @StateObject var tagCollectionByCombine: TagCollectionByCombine = .init() var tagCollectionByObservation:TagCollectionByObservation = .init() $PNCJOF </FX>0CTFSWBUJPO ᶃঢ়ଶର৅ʹࢦఆ͢Δ4XJGU"UUSJCVUFT ᶄಛʹهड़ͳ͠

E σʔλιʔεΦϒδΣΫτ $PNCJOF </FX>0CTFSWBUJPO import Foundation class TagCollectionByCombine: ObservableObject {
@Published var collection: [Tag] = .defaultTags() var collectionCount: Int { collection.count } } import Observation @Observable class TagCollectionByObservation { var collection: [Tag] = .defaultTags() var collectionCount: Int { collection.count } } ᶄ!0CTFSWBCMFΛΫϥεͷલʹ෇͚Δ ᶃ0CTFSWBCMF0CKFDUͷ೿ੜΫϥε

F ؍ଌՄೳͳσʔλͷ౉͠ํ $PNCJOF </FX>0CTFSWBUJPO ContentViewByCombineFromParameter(tagCollection: tagCollectionByCombine) ContentViewByCombineFromEmvironment() .environmentObject(tagCollectionByCombine) ContentViewByObservationFromParameter(tagCollection: tagCollectionByObservation)
ContentViewByObservationFromEmvironment() .environment(tagCollectionByObservation) FOWJSPONFOU0CKFDUͱFOWJSPONFOUͷҧ͍

G σʔλιʔεΛ؍ଌ͢Δଆͷఆٛ $PNCJOF </FX>0CTFSWBUJPO struct ContentViewByCombineFromParameter: View { @ObservedObject var
tagCollection: TagCollectionByCombine } struct ContentViewByCombineFromEmvironment: View { @EnvironmentObject var tagCollection: TagCollectionByCombine } struct ContentViewByObservationFromParameter: View { var tagCollection: TagCollectionByObservation } struct ContentViewByObservationFromEmvironment: View { @Environment(TagCollectionByObservation.self) var tagCollection: } ᶃҾ਺Ͱ౉͞ΕΔ৔߹ ᶄ؀ڥม਺Ͱ౉͞ΕΔ৔߹ ᶅ؀ڥม਺Ͱ౉͞ΕΔ৔߹ͷΈࢦఆ

struct ContentViewDependOnViewLifecycle: View { @StateObject var tagCollection: TagCollectionByCombine = .init()
} H 7JFXͷม਺ͱͯ͠ಠཱͯ͠࢖͏ $PNCJOF </FX>0CTFSWBUJPO ᶃม਺ఆٛͰ͸!4UBUF0CKFDU͕ඞཁ struct ContentViewByObservationDependOnViewLifecycle: View { var tagCollection: TagCollectionByObservation = .init() } ᶄಛʹࢦఆͳ͠

$PNCJOFͱ0CTFSWBUJPOͷҧ͍ هड़͢ΔՕॴ͸ͦΕ΄ͲมΘΒͣ $PNCJOF 0CTFSWBUJPO ϑϨʔϜϫʔΫ 'PVOEBUJPO $PNCJOF͸ඪ४ѻ͍ 0CTFSWBUJPO σʔλιʔεͷఆٛ !4UBUF0CKFDU
ಛʹͳ͠ σʔλιʔεͷએݴ 0CTFSWBCMF0CKFDUͷ೿ੜΫϥε ؍ଌ͍ͤͨ͞ଐੑʹ!1VCMJTIFEࢦఆ Ϋϥεͷઌ಄ʹ!0CTFSWBCMF Կ΋ࢦఆ͠ͳ͍ͱ؍ଌ͢Δଐੑʹ σʔλιʔεΛ؍ଌ͢Δ ଆͷఆٛ !0CTFSWFE0CKFDU !&OWJSPONFOU0CKFDU ؀ڥม਺Ͱ౉͞ΕΔ৔߹ͷΈ !&OWJSPONFOU σʔλόΠϯσΟϯά ৗʹ༗ޮ !#JOEBCMFΛࢦఆ͠ͳ͍ͱ༗ޮ ʹͳΒͳ͍

هड़ํ๏͕एׯมΘ͍ͬͯΔ͕ ϝϦοτ͸͋Δͷ͔

0CTFSWBUJPOͷૂ͍

$PNCJOF ʙ Ͱ͸γϯϓϧʹ࣮ݱͰ͖ͳ͍͜ͱ͕ଟ͍ w σʔλ؍ଌͷͨΊʹ4XJGU"UUSJCVUFTΛ෇Ճ͢Δඞཁ͕͋Δ w !4UBUF0CKFDUɺ!0CTFSWFE0CKFDUɺ!&OWJSPONFOU0CKFDU w ഑ྻ ू߹Λ͞Βʹू߹
Λͦͷ··σʔλ؍ଌର৅ʹͰ͖ͳ͍ w 4XJGU6*Ͱ஋ΛऔΓѻ͏4XJGU"UUSJCVUFTͱিಥ͍ͯ͠Δ w !4UBUF w !"QQ4UPSBHF w !4DFOF4UPSFBHF

഑ྻ ू߹Λ͞Βʹू߹ Λͦͷ··σʔλ؍ଌର৅ʹ $PNCJOF </FX>0CTFSWBUJPO @main struct ObservationCombineCodeComparisonApp: App {
@StateObject var tagCollectionByCombine: [TagCollectionByCombine] = .init() } ΤϥʔͱͳΔ @main struct ObservationCombineCodeComparisonApp: App { var tagCollectionByObservation:[TagCollectionByObservation] = .init() } Τϥʔʹ͸ͳΒͣͦΕͧΕ؍ ଌՄೳͳσʔλΦϒδΣΫτ ͱͯ͠ػೳ

4XJGU6*Ͱ஋ΛऔΓѻ͏4XJGU"UUSJCVUFTͱিಥ͍ͯ͠Δ w !4UBUF w !"QQ4UPSBHF w !4DFOF4UPSFBHF ᶃ7JFX಺Ͱঢ়ଶ؂ࢹͰ͖Δม਺ʹࢦఆ ᶄΞϓϦͷετϨʔδ͔Βσʔλऔಘ ᶅγʔϯͷण໋಺Ͱ༗ޮͳσʔλ͔Βࢀর
σʔλ؍ଌͷͨΊ͚ͩʹ4XJGU"UUSJCVUFTΛ઎༗͞ΕΔͱଞͷ༻్ͷ 4XJGU"UUSJCVUFTͷ࢖༻Λ๦͓͛ͯΓճආࡦͷͨΊͷίʔυهड़͕ඞཁ import Foundation class TagCollectionByCombine: ObservableObject { @Published var collection: [Tag] = .defaultTags() var collectionCount: Int { collection.count } }

4XJGU"UUSJCVUFTͱ͸Կ IUUQTTQFBLFSEFDLDPNOPUPSPJEBQQMFHBZBSJUBJGBOHUJTXJGUBUUSJCVUFT

0CTFSWBUJPOొ৔ͷഎܠ w 4XJGU6*ެ։࣌ ʙ w $PNCJOF w 4XJGU"UUSJCVUFT w
Ϋϥε೿ੜ w 4XJGU.BDSPT ొ৔ w 0CTFSWBUJPOʹΑΔσʔλ؍ଌͷ࢓૊ΈΛ࣮ݱ w ա౓ʹ4XJGU"UUSJCVUFTґଘ͠ͳ͘ͳͬͨ

0CTFSWBUJPOͷͦͷଞͷಛ௃ w σʔλόΠϯσΟϯά͸Φϓγϣϯࢦఆ΁ w $PNCJOFͰ͸σʔλΦϒδΣΫτ͸σϑΥϧτͰ༗ޮ w !#JOEJOHΛ࢖͏ͱΦϒδΣΫτʹؚ·ΕΔσʔλΛࢀরɺมߋՄೳʹ w 0CTFSWBUJPOͰ͸σʔλΦϒδΣΫτͷࢀরଆͰ!#JOEBCMFࢦఆ͕ඞཁ w
σʔλΦϒδΣΫτͷଐੑ͸σϑΥϧτͰ؍ଌର৅ʹ w !0CTFSWBUJPO*HOPSFEΛࢦఆ͠ͳ͍ݶΓৗʹ؍ଌର৅ѻ͍

·ͱΊ wσʔλ؍ଌͷ࢓૊Έͱͯ͠0CTFSWBUJPO͕ొ৔͠·ͨ͠ w4XJGU6*޲͚ w$PNCJOFͱࣅ௨ͬͨهड़͕Ͱ͖Δ͕ผ෺ w೥4XJGU6*ൃද౰ॳ͔Βͷෆຬ఺ ໃ६఺ Λվળ

ࢀߟ w %JTDPWFS0CTFSWBUJPOJO4XJGU6*88%$ 7JEFPT"QQMF%FWFMPQFS w IUUQTEFWFMPQFSBQQMFDPNXXED w ʲ88%$ʳ%JTDPWFS0CTFSWBUJPOJO4XJGU6*ʢ೔ຊ ޠ༁ʣJ1IPOFΞϓϦ։ൃߨ࠲ʛ$PEF$BOEZΦϯϥΠ ϯϓϩάϥϛϯάεΫʔϧ
w IUUQTCMPHDPEFDBOEZDPN EJTDPWFS@PCTFSWBUJPO@JO@TXJGUVJ w ͞Α͏ͳΒɺ$PNCJOFɻͦͯ͜͠Μʹͪ͸ɺ 0CTFSWBUJPOɻ2JJUB w IUUQTRJJUBDPNMPWFFJUFNT ECCBCCD w 8IBU`TOFXJO4XJGU88%$7JEFPT"QQMF %FWFMPQFS w IUUQTEFWFMPQFSBQQMFDPNXXED UJNF w %BUB'MPX5ISPVHI4XJGU6*88%$7JEFPT "QQMF%FWFMPQFS w IUUQTEFWFMPQFSBQQMFDPNWJEFPTQMBZ XXED UJNF w "QQMF͕ ΍Γ͍ͨ์୊4XJGU"UUSJCVUFT4QFBLFS %FDL w IUUQTTQFBLFSEFDLDPNOPUPSPJEBQQMFHB ZBSJUBJGBOHUJTXJGUBUUSJCVUFT w Αͤ͋ͭΊ4XJGU4XJGU4QFBLFS%FDL w IUUQTTQFBLFSEFDLDPNOPUPSPJE ZPTFBUVNFTXJGUTXJGUEPU

SwiftUIむけに 整理された状態監視 Observation

SwiftUIむけに 整理された状態監視 Observation

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SwiftUIむけに整理された状態監視 Observation

SwiftUIむけに整理された状態監視 Observation