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Combine入門
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shtnkgm
June 11, 2020
Programming
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Combine入門
AppleのCombineフレームワークの基本的な内容について
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Transcript
! Combineೖ 2020.6.11 iOSLT / @shtnkgm 1
Combineͱ • Swift͚Framework • WWDC2019Ͱൃද • iOS 13.0+ • ඇಉظॲཧΛѻ͏ͷ
2
UIKitͷඇಉظॲཧ • Taregt/ActionʢTimer, @IBAction ...ʣ • NotificationCenter • URLSession •
KVOʢKey-value observingʣ • Callback࣮ʢDelegate, Closureʣ 3
ඇಉظॲཧʹ͓͚Δ՝ • ωετͨ͠Closure Callbackࠈ • Delegateॻ͘ͷಡΉͷΊΜͲ͍͘͞ࠈ • ඇಉظΠϕϯτͷछྨ࣮͍Ζ͍ΖɺྲྀΕ͕Θ͔Βͳ͘ͳ Δ 4
Combine͜ΕΒͷඇಉظॲཧΛ Ұݩతɺએݴతʹѻ͏ͨΊͷAPI 5
ओͳAPI • Publisher • Subscriber • Operator 6
Publisher • Τϥʔ͕ͲͷΑ͏ʹൃੜ͢Δ͔Λఆٛ • SubscriberͷొΛՄೳʹ͢Δʢߪಡʣ • ࣮ܕʢstructʣ 7
Publisherͷఆٛ protocol Publisher { associatedtype Output associatedtype Failure: Error //
Subscriberͷొ func subscribe<S>(_ subscriber: S) where S : Subscriber, Self.Failure == S.Failure, Self.Output == S.Input } 8
NotificationCenterͰͷPublisher࣮ྫ extension NotificationCenter { struct Publisher: Combine.Publisher { typealias Output
= Notifiation typealias Failure = Never // Τϥʔͳ͍߹Neverܕ init(center: NotificationCenter, name: Notification.Name, object: Any? = nil) } } 9
ฦ͞ͳ͍ͷͬͯVoid͡Όͳ͍ͷʁ 10
Neverܕ public enum Never {} • ࣮caseͳ͠enum • ͭ·ΓΛͭ͘Εͳ͍͜ͱΛදݱ 11
Voidܕ public typealias Void = () • ࣮ۭͷλϓϧͷΤΠϦΞε • ͭ·ΓۭͷλϓϧΛฦ͍ͯ͠Δ
12
fatalErrorͷΓNeverܕ class ViewController: UIViewController init() { ... } required init?(coder
aDecoder: NSCoder) { // NeverܕΛฦ͢͜ͱͰϓϩάϥϜऴྃ fatalError("init(coder:) has not been implemented") } func hoge() -> Int { // ΓͷܕݕࠪߦΘΕͳ͍ͷͰ // ͜ΕͰίϯύΠϧ͕௨Δ fatalError() } } 13
Subscriber • ͱྃΛड͚औΔ • ࢀরܕʢclassʣ 14
Subscriberͷఆٛ protocol Subscriber { associatedtype Input associatedtype Failure : Error
// SubscriptionΛड͚औΔ func receive(subscription: Subscription) // ೖྗΛड͚औΔ func receive(_ input: Self.Input) -> Subscribers.Demand // ྃΛड͚औΔʢ༗ݶͷ߹ʣ func receive(completion: Subscribers.Completion<Self.Failure>) } 15
Subscriberͷ࣮ྫʢAssignʣ ࢦఆ͞ΕͨΩʔύεʹΛηοτ͢ΔSubscriber // Subscribersͨͩͷnamespaceͱͯ͠ͷenum // AssignͷଞʹɺDemand, Completion, Sink͕͋Δ extension Subscribers
{ class Assign<Root, Input>: Subscriber, Cancellable { typealias Faiure = Never init(object: Root, keyPath: ReferenceWritableKeyPath<Root, Input>) } } 16
Operator • Publisherϓϩτίϧʹ४ڌ • ͕มԽ͢Δ;Δ·͍Λఆٛ • ܕʢstructʣ 17
Operatorͷ࣮ྫʢMapʣ // ͜Εnamespace // MapҎ֎ʹSequence, Catch, ReceiveOn, SubscribeOn...ͳͲΊͬͪΌ͋Δ extension Publishers
{ struct Map<Upstream, Output> where Upstream : Publisher { typealias Failure = Upstream.Failure let upstream: Upstream let transform: (Upstream.Output) -> Output } } 18
OperatorͰͰ͖Δ͜ͱͷҰྫ • ؔతͳͷม • Ϧετૢ࡞ • ΤϥʔϋϯυϦϯά • εϨουɺΩϡʔΠϯάॲཧʢαϒεϨουॲཧʣ •
εέδϡʔϦϯάʢλΠϚʔॲཧʣ 19
Publisher, Subscriber, OperatorΛͬͯΈΔ ຐ๏ֶߍͱֶ class Wizard { var grade: Int
init(grade: Int) { self.grade = grade } } let merlin = Wizard(grade: 5) 20
Publisher, Subscriber, OperatorΛͬͯΈΔ let graduationPublisher = NotificationCenter.Publisher(center: .default, name: .graduated,
object: merlin) let gradeSubscriber = Subscribers.Assign(object: merlin, keyPath: \.grade) let converter = Publishers.Map(upstream: graduationPublisher) { note in return note.userInfo?["NewGrade"] as? Int ?? 0 } converter.subscribe(gradeSubscriber) 21
Publisherͷmap, assign֦ு extension Publisher { func map<T>(_ transform: @escaping (Self.Output)
-> T) -> Publishers.Map<Self, T> { return Publishers.Map(upstream: self, transform: transform) } } extension Publisher where Self.Failure == Never { func assign<Root>(to keyPath: ReferenceWritableKeyPath<Root, Self.Output>, on object: Root) -> AnyCancellable { return Subscribers.Assign<Self, Input>(object: object, keyPath: keyPath) } } 22
ϝιουνΣΠϯͰΑΓએݴతʹ let cancellable = NotificationCenter.default.publisher(for: .graduated, object: merlin) .map {
note in return note.userInfo?["NewGrade"] as? Int ?? 0 } .assign(to: \.grade, on: merlin) 23
ϝιουνΣΠϯͰΑΓએݴతʹ compactMapfilterɺprefixͳͲArrayͰݟ׳Εͨؔ let cancellable = NotificationCenter.default.publisher(for: .graduated, object: merlin) .compactMap
{ note in return note.userInfo?["NewGrade"] as? Int } .filter { $0 >= 5 } .prefix(3) .assign(to: \.grade, on: merlin) 24
௨৴ॲཧʹ͑ͦ͏ͳͷଟ͍ https://developer.apple.com/documentation/combine/publishers • Zip, Zip3, Zip4, CombineLatest: ͪ߹Θͤ • Decode:
σίʔυॲཧ • Retry: ϦτϥΠ • Throttle, Debounce: ࿈ଓ͢ΔΠϕϯτΛݮΒ͢ʢ࿈ଧɺΠϯΫϦϝϯλϧαʔ νʣ • Timeout: λΠϜΞτ 25
௨৴ॲཧͷ࣮ྫ 26
class UserRepository { private var subscriptions = Set<AnyCancellable>() func fetchUsers()
-> Future<[User], UserAPIError> { return Future<[User], UserAPIError> { [unowned self] promise in URLSession .shared .dataTaskPublisher(for: url) .debounce(for: .milliseconds(500), scheduler: RunLoop.main) .retry(3) .map { $0.data } .decode(type: [User].self, decoder: JSONDecoder()) .receive(on: DispatchQueue.main) .sink(receiveCompletion: { _ in promise(.failure(.somethingWrong)) }, receiveValue: { users in promise(.success(users)) }) .store(in: &self.subscriptions) } } func cancelAll() { subscriptions.forEach { $0.cancel() } } } 27
Viewͱͷ࿈ܞ • SwiftUI • ObservableObject/Published • UIKit • UICollectionViewDiffableDataSource •
UITableViewDiffableDataSource 28
noppefoxwolf/Combinative • https://github.com/noppefoxwolf/Combinative • UIKitͷUIControllʹCombineΛ֦ு let button = UIButton() button.cmb.tap.sink
{ (button) in // do something } @IBOutlet weak var textField: UITextField! textField.cmb.text.sink { (text) in print(text) } 29
͓ΘΓ 30