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RxSwift Operators Tips
2017/03/1 CA.swift
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About Me
ҏ౻ɹګฏ
Github : KyoheiG3
Twitter : @KyoheiG3
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͖Ε͍ͳͷྲྀΕΛकΔͨΊͷ੍ͦͷᶃ
Λஅ͠ͳ͍
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͖Ε͍ͳͷྲྀΕΛकΔͨΊͷ੍ͦͷᶃ
→ DisposeBagΛෳʹ͚ͳ͍
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flatMap
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flatMap
Observable͔Βૹ৴͞ΕͨΞΠςϜΛObservablesʹม͠ɺ
ͦͷޙͦΕΒ͔Βૹ৴͞ΕΔΞΠςϜΛ̍ͭͷObservableม
͢Δɻ
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flatMap
͔ΒɺྲྀΕΛͭͳ͙
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Bad Stream
botton.rx.tap
.subscribe(onNext: {
URLSession.shared.rx.json(request: request)
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
})
.addDisposableTo(disposeBag)
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Good Stream
botton.rx.tap
.flatMap {
URLSession.shared.rx.json(request: request)
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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flatMapͷಛ
લճͷΠϕϯτ͕ऴ͍ྃͯ͠ͳͯ͘ΞΠςϜ͕ετϦʔϜʹྲྀ
ΕΔͷͰɺಉ͡ॲཧ͕ෳճߦΘΕΔՄೳੑ͕͋Δɻ
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ඇಉظॲཧͰΓ͍ͨ͜ͱ
௨৴ͳͲͷඇಉظॲཧɺॲཧதετϦʔϜΛྲྀ͞ͳ͍ɺ·
ͨ࠷৽ͷετϦʔϜ͚ͩΛྲྀ͍ͨ͠ɻ
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flatMapLatest
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flatMapLatest
ͷྲྀΕΛஅͪͬͯɺ࣍ͷͱྲྀΕΛͭͳ͙
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Bad Stream
botton.rx.tap
.subscribe(onNext: {
requestDisposeBag = DisposeBag()
URLSession.shared.rx.json(request: request)
.subscribe(onNext: { ... })
.addDisposableTo(requestDisposeBag)
})
.addDisposableTo(disposeBag)
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Good Stream
botton.rx.tap
.flatMapLatest {
URLSession.shared.rx.json(request: request)
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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flatMapLatestͷಛ
৽͍͠Πϕϯτ͕ىͬͨ͜ΒલͷΠϕϯτΛഁغͯ࣍͠ͷΠϕϯ
τΛߦ͏ͷͰɺ୯Ұͷॲཧ͔͠ߦΘΕͳ͍ɻ
TimerIntervalͳͲͷඇಉظॲཧɺflatMapLatestͱ૬ੑ͕
Α͍ɻ
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Timer Stream
botton.rx.tap
.flatMapLatest {
Observable.timer(1, scheduler: scheduler)
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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debounceͱॲཧ͕Α͘ࣅ͍ͯΔ
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Debounce
botton.rx.tap
.debounce(1, scheduler: scheduler)
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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DebounceͱTimer Streamͷҧ͍
ετϦʔϜʹྲྀΕ͖ͯͨΛͱʹintervalΛม͑Δ͜ͱ͕Ͱ
͖Δɻ
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έʔεͦͷᶃ
ΞΠςϜΛड͚औ͔ͬͯΒɺҰఆ࣌ؒޙʹΞΠςϜΛετϦʔϜ
ʹྲྀ͍ͨ͠ɻԆ࣌ؒΞΠςϜͷ༰ʹΑͬͯஅ͢Δɻ
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{
"num": 10,
"title": "Timer Stream"
}
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Timer Stream
botton.rx.tap
.flatMapLatest {
URLSession.shared.rx.json(request: request)
}
.flatMapLatest { json -> Observable in
Observable.timer(json["num"] as! Int, scheduler: scheduler)
.map { _ in json }
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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έʔεͦͷᶄ
ΞΠςϜΛड͚औͬͨΒετϦʔϜʹྲྀ͕͢ɺҰఆ࣌ؒޙʹnil
ΛετϦʔϜʹྲྀ͍ͨ͠ɻԆ࣌ؒΞΠςϜͷ༰ʹΑͬͯ
அ͢Δɻ
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έʔεͦͷᶄ
startWithΛ͏
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Timer Stream
botton.rx.tap
.flatMapLatest {
URLSession.shared.rx.json(request: request)
}
.flatMapLatest { json -> Observable in
Observable.timer(json["num"] as! Int, scheduler: scheduler)
.map { _ in nil }
.startWith(json)
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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flatMapFirst
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flatMapFirst
ͷྲྀΕ͕ࢭ·Δ·Ͱɺ࣍ͷͭͳ͕ͳ͍
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Bad Stream
var requesting = false
botton.rx.tap
.subscribe(onNext: {
if requesting { return }
requesting = true
requestDisposeBag = DisposeBag()
URLSession.shared.rx.json(request: request)
.subscribe(onNext: {
requesting = false
})
.addDisposableTo(requestDisposeBag)
})
.addDisposableTo(disposeBag)
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Good Stream
botton.rx.tap
.flatMapFirst {
URLSession.shared.rx.json(request: request)
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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flatMapFirstͷಛ
࠷ॳʹૹ৴͞ΕͨΞΠςϜͷॲཧ͕ྃ͢Δ·Ͱɺͦͷޙʹ
ૹΒΕͨΞΠςϜΛൖ͠ͳ͍ͷͰɺ୯Ұͷॲཧ͔͠ߦΘΕͳ
͍ɻ
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Timer Stream
botton.rx.tap
.flatMapFirst {
Observable.timer(1, scheduler: scheduler)
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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throttleͱॲཧ͕Α͘ࣅ͍ͯΔ
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Throttle
botton.rx.tap
.throttle(1, scheduler: scheduler)
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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Throttleͷҙ
throttleετϦʔϜ1ൃͷΞΠςϜ͕ྲྀΕͯ͘ΔͬΆ͍ɻ
ੲྲྀΕͯ͜ͳ͔ͬͨͷͰɺ͔ͨ͠͠ΒόʔδϣϯʹΑͬͯ
มΘΔ͔ɻ
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͖Ε͍ͳͷྲྀΕΛकΔͨΊͷ੍ͦͷᶄ
ʹͷΛ͛ೖΕͳ͍
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͖Ε͍ͳͷྲྀΕΛकΔͨΊͷ੍ͦͷᶄ
→ ΫϩʔδϟͰselfΛࢀরͤ͞ͳ͍
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selfΛࢀরͤ͞ͳ͍ํ๏
ෳͷετϦʔϜΛ߹ɺ͋Δ͍ঢ়ଶΛΔඞཁ͕͋Δɻ
RxͷoperatorsҰཡͳͲΛ֬ೝͯ͠Έͯɺ(x, y)Έ͍ͨʹ2ͭͷ
Λࢀর͍ͯ͠ΔΑ͏ͳoperator߹νϟϯεɻ
શʹࢀর͠ͳ͍ͷ͍͠ͷͰɺͰ͖ΔݶΓͰͬͯΈΔɻ
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withLatestFrom
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withLatestFrom
͋ΔετϦʔϜʹରͯ͠ɺผͷετϦʔϜͷ࠷৽ͷΞΠςϜΛ߹
͢Δɻ
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Bad Stream
let other = Variable(0)
botton.rx.tap
.subscribe(onNext: { [weak self] in
self?.other.asObservable()
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
})
.addDisposableTo(disposeBag)
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Self Reference
let other = Variable(0)
botton.rx.tap
.subscribe(onNext: { [weak self] in
print(self?.other.value)
})
.addDisposableTo(disposeBag)
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Good Stream
let other = Variable(0)
botton.rx.tap
.withLatestFrom(other.asObservable())
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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withLatestFromͷಛ
subscribeޙʹετϦʔϜʹྲྀΕͨ࠷৽ͷΞΠςϜͰ͋Εɺ
VariableͷΑ͏ʹΛอ͍࣋ͯ͠ͳ͍֮ͯ͑ͯͯ͘͘ΕΔͷ
Ͱ߹͢Δ͜ͱ͕Ͱ͖Δɻ
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Good Stream
let other = PublishSubject()
botton.rx.tap
.withLatestFrom(other)
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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scan
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scan
Observable͔Βૹ৴͞ΕΔΞΠςϜʹ࿈ଓͯؔ͠Λద༻͢
Δɻ
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Bad Stream
let some = Variable(0)
botton.rx.tap
.flatMapLatest {
URLSession.shared.rx.json(request: request)
}
.map { [weak self] json in
let num = json["num"] as! Int
if let value = self?.some.value {
let new = value + num
self?.some.value = new
return new
}
return 0
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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Good Stream
botton.rx.tap
.flatMapLatest {
URLSession.shared.rx.json(request: request)
}
.map { json in json["num"] as! Int }
.scan(0) { some, new in
some + new
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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scanͷಛ
scanΛߦ͏͜ͱͰɺ͋ΔετϦʔϜʹରͯ͠ผͷΞΠςϜΛྲྀ
͢͜ͱ͕Ͱ͖Δɻ
ετϦʔϜʹྲྀͨ͠ΞΠςϜอ࣋͞Ε͍ͯΔͷͰɺ࣍ճετ
ϦʔϜʹΞΠςϜ͕ྲྀΕ͖ͯͨࡍʹɺอ͍࣋ͯ͠ΔΞΠςϜͱ
ྲྀΕ͖ͯͨΞΠςϜͷ྆ํΛಘΔ͜ͱ͕Մೳɻ
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scanͷಛ
݅ʹ߹Θͳ͚ΕಉҰͷΞΠςϜΛྲྀ͠ଓ͚ͯɺ
distinctUntilChangedΛ࣮ߦͯ͠ॲཧΛল͘͜ͱͰ͖Δɻ
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Good Stream
botton.rx.tap
.flatMapLatest {
URLSession.shared.rx.json(request: request)
}
.map { json in json["num"] as! Int }
.scan(0) { some, new in
new > some ? new : some
}
.distinctUntilChanged()
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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scanͷಛ
อ͍࣋ͯ͠ΔΞΠςϜ͕มΘΔࡍʹɺݹ͍ΞΠςϜΛར༻ͯ͠ॲ
ཧΛߦ͏Α͏ͳ͜ͱՄೳɻ
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Good Stream
botton.rx.tap
.flatMapLatest {
URLSession.shared.rx.json(request: request)
}
.map { json in json["num"] as! Int }
.scan(0) { some, new in
if new > some {
...
return new
}
return some
}
.distinctUntilChanged()
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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distinctUntilChanged
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distinctUntilChanged
ॏෳͨ͠ΞΠςϜͷ߹ૹ৴͠ͳ͍Α͏ʹ͢ΔΦϖϨʔλɻ
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distinctUntilChanged
botton.rx.tap
.flatMapLatest {
URLSession.shared.rx.json(request: request)
}
.map { json in json["num"] as! Int }
.distinctUntilChanged()
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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distinctUntilChangedͷಛ
ΞΠςϜ͕EquatableͰͳ͍߹ΫϩʔδϟΛड͚औͬͯͦ
ͷΫϩʔδϟΛ࣮ߦ͠ɺΓ͕trueͷ͏ͪॲཧΛܧଓ͠ͳ
͍Α͏ͳৼΔ͍Λ͍ͯ͠Δɻ
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distinctUntilChangedͷಛ
ετϦʔϜʹྲྀΕͨΞΠςϜΛอ͓͖࣋ͯ͠ɺ࣍ճετϦʔϜʹ
ΞΠςϜ͕ྲྀΕ͖ͯͨࡍʹ৽چ྆ํͷΞΠςϜΛಘΔ͜ͱ͕Մ
ೳɻ
ॳظΛؾʹ͠ͳ͍ͷͰ͋Εɺscanͱಉ͡Α͏ͳॲཧΛ͏
গ͘͠ॻ͘͜ͱͰ͖Δɻ
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distinctUntilChanged
botton.rx.tap
.flatMapLatest {
URLSession.shared.rx.json(request: request)
}
.map { json in json["num"] as! Int }
.distinctUntilChanged { old, new in
if (new <= old) == false {
...
}
return new <= old
}
.subscribe(onNext: { ... })
.addDisposableTo(disposeBag)
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·ͱΊ
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No content
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Thanks!