Combine And SwiftUI

Combine と SwiftUI

帰ってきた関西モバイルアプリ研究会#2 - connpass
https://kanmoba.connpass.com/event/134059/

Combine と SwiftUI について話しました #関モバ - usami-kの日記
https://usami-k.hatenablog.com/entry/2019/06/13/005041

1. Combine ͱ SwiftUI USAMI Kosuke Fenrir Inc.
2. Combine • WWDC19 Ͱൃද͞Εͨ Reactive ϑϨʔϜϫʔΫ • υΩϡϝϯτʹ͸ "Reactive" ͱ͸ॻ͍ͯͳ͍͕ • RxSwift ΍ ReactiveSwift ʹͱ͔ͬͯΘΔଘࡏ • ͨͩ͠ iOS 13 Ҏ߱Ͱ͔͠ಈ࡞͠ͳ͍
3. Combine ͷ༻ޠ • ֓೦͸ Rx (RxSwift) ʹ͍ۙɺ༻ޠ͸ҟͳΔ Combine RxSwift Publisher Observable Subscriber Observer CurrentValueSubject BehaviorSubject PassthroughSubject PublishSubject
4. Publisher protocol protocol Publisher { associatedtype Output associatedtype Failure: Error } • Τϥʔͷܕ͕໌ࣔతͳͷ͸ ReactiveSwift ͱಉ༷ͷར఺ • ྫ͑͹ Failure Λ Never ʹ͢Δ͜ͱͰɺΤϥʔग़ྗ͠ͳ͍ Publisher ͕ఆٛͰ͖ΔʢRxSwift ͸͜ͷ͋ͨΓ͕ऑ͍ʣ
5. Subscriber protocol protocol Subscriber { associatedtype Input associatedtype Failure: Error } protocol Publisher { func subscribe<S : Subscriber>(_ subscriber: S) where Output == S.Input, Failure == S.Failure } • subscribe ʹ੩తܕνΣοΫ͕͋Δ
6. Just / Sequence / ... • enum Publishers ʹఆٛࡁΈͷ Publisher ͕͋Δ • Publishers.Empty • Publishers.Fail • Publishers.Just • Publishers.Sequence • ͳͲ
7. Future • Publishers.Future • ͻͱ͚ͭͩ஋Λฦͯ͠ऴྃ͢Δ • Promise ͷΑ͏ͳ࢖͍ํ͕૝ఆ͞Ε͍ͯΔ
8. Operators • Publisher ͕֤छͷ Operator Λ࣋ͭ • map / flatMap / filter / ... • combineLatest / merge / zip / ... • catch / retry / ... • debounce / delay / ..
9. tryMap • tryMap / tryFilter / ... • ΤϥʔΛ throw ͨ͠৔߹ʹ Publisher ͷΤϥʔग़ྗʹ ͯ͘͠ΕΔ .tryMap { data in let decoder = JSONDecoder() try decoder.decode(Hoge.self, from: data) }
10. decode • decode ͱ͍͏ɹOperator ͕͋Δ • ࣮͸͖ͬ͞ͷίʔυ͸͜͏ॻ͚Δ .decode(Hoge.self, JSONDecoder())
11. UI ͱͷ࿈ܞ • Combine ͱ SwiftUI Λ૊Έ߹Θͤͯ࢖͏ • UIKit ͱ૊Έ߹ΘͤΔ͜ͱ΋ෆՄೳͰ͸ͳ͍͕ɾɾɾ
12. BindableObject protocol protocol BindableObject { associatedtype PublisherType : Publisher where PublisherType.Failure == Never var didChange: PublisherType { get } }
13. BindableObject Λ࡞Δ class Hoge : BindableObject { let didChange = PassthroughSubject<Void, Never>() var value: String { didSet { didChange.send() } } }
14. SwiftUI ͱͷ bind struct HogeView : View { @ObjectBinding var model: Hoge var body: some View { Text($model.value) } } HogeView(model: hogeInstance)
15. @ObjectBinding • Swift ͷ Property Delegate ػೳʢProperty Wrapper ͱ΋ݺ͹Ε͍ͯΔʣ • SwiftUI Ͱ͸ଞʹ @Binding ΍ @State ͕͋Δ • BindableObject Λ౉͢ͱɺࣗಈతʹ didChange Λ؂ࢹ͠ ͯ஋Λߋ৽ͯ͘͠ΕΔ
16. Combine + SwiftUI ͷະདྷ • MVC ͔Βͷ୤٫ • ViewController ΍ Storyboard ͔Βͷ୤٫ • Flux ͱ૬ੑ͕ྑ͍ʁ • Action : Publisher • State ͔Β View ΁ͷ൓ө : ObjectBinding