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首先,何為
RxSwift?
RxSwift是ReactiveX的Swift版本,一個(gè)響應(yīng)式變成框架。傳送門(mén)
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開(kāi)始之前,先介紹兩個(gè)
function,并沒(méi)有什么實(shí)質(zhì)性作用,只是為了方便學(xué)習(xí)演示
/**
延遲`delay`時(shí)長(zhǎng)之后執(zhí)行`closure`閉包
- parameter delay: 閉包延遲執(zhí)行時(shí)間
- parameter closure: 返回值`Void`的閉包
*/
public func delay(_ delay: Double, closure: @escaping (Swift.Void) -> Swift.Void)
/**
起到一個(gè)分割線作用
- parameter description: example 簡(jiǎn)介
- parameter action: 返回值`Void`的閉包
*/
public func example(_ description: String, action: (Swift.Void) -> Swift.Void)
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RxSwift基礎(chǔ)
Observable:Observable是觀察著模式中的被觀察對(duì)象,相當(dāng)于一個(gè)事件序列GeneratorType,它會(huì)向它的訂閱者發(fā)送事件信息,
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next():一個(gè)新的事件 -
complete():完成事件 -
error(): 錯(cuò)誤事件
多數(shù)情況都是對(duì)不同的
Observable進(jìn)行subscribe操作,并在接收到事件后進(jìn)行相應(yīng)的操作
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名詞解釋
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DisposeBag
相當(dāng)于一個(gè)
autoreleasepool(自動(dòng)釋放池),對(duì)觀察者進(jìn)行管理,在適當(dāng)?shù)臅r(shí)候銷(xiāo)毀觀察者
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Observable
Observables will not execute their subscription closure unless there is a subscriber
Observables只有被訂閱之后才會(huì)被執(zhí)行,否則不予執(zhí)行
```
example("一個(gè)未被訂閱的Observable") {
_ = Observable<String>.create { observerOfString -> Disposable in
print("This will never be printed")
observerOfString.on(.next("??"))
observerOfString.on(.completed)
return Disposables.create()
}
}
//不會(huì)打印任何數(shù)據(jù),因?yàn)樵揙bservable沒(méi)有被訂閱
- ###### subscribe
> subscribe是訂閱`sequence`發(fā)出的事件，比如`next`事件，`error`事件等。而`subscribe(onNext:)`是監(jiān)聽(tīng)`sequence`發(fā)出的`next`事件中的`element`進(jìn)行處理，他會(huì)忽略`error`和`completed`事件。相對(duì)應(yīng)的還有`subscribe(onError:) `和 `subscribe(onCompleted:)`
```
example("被訂閱的Observable") {
let disposeBag = DisposeBag()
Observable<String>.create { observerOfString in
print("Observable created")
observerOfString.on(.next("??"))
observerOfString.on(.completed)
return Disposables.create()
}
.subscribe { event in
print(event)
}.addDisposableTo(disposeBag)
}
執(zhí)行結(jié)果:
--- 被訂閱的Observable ---
Observable created
next(??)
completed
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Creating and Subscribing to Observables/ 創(chuàng)建并訂閱Observables -
never
創(chuàng)建一個(gè)空序列,不發(fā)送任何事件
example("never") {
let disposeBag = DisposeBag()
let neverSequence = Observable<String>.never()
neverSequence
.subscribe { _ in
print("This will never be printed")
}
.addDisposableTo(disposeBag)
}
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empty
一個(gè)空的序列，它只發(fā)送 .Completed 消息
example("empty") {
let disposeBag = DisposeBag()
Observable<Int>.empty()
.subscribe { event in
print(event)
}
.disposed(by: disposeBag)
}
//執(zhí)行結(jié)果:
--- empty example ---
completed
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just
只包含一個(gè)元素的序列,發(fā)送一個(gè)next事件和completed事件
example("just") {
let disposeBag = DisposeBag()
Observable.just("??")
.subscribe { event in
print(event)
}
.disposed(by: disposeBag)
}
//執(zhí)行結(jié)果:
--- just example ---
next(??)
completed
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of
將所有元素依次轉(zhuǎn)換為序列發(fā)送
example("of") {
let disposeBag = DisposeBag()
Observable.of("??", "??", "??", "??")
.subscribe(onNext: { element in
print(element)
})
.disposed(by: disposeBag)
}
//執(zhí)行結(jié)果
--- of example ---
??
??
??
??
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from
從數(shù)組或字典或集合的所有元素創(chuàng)建序列發(fā)送
example("from") {
let disposeBag = DisposeBag()
Observable.from(["??", "??", "??", "??"])
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
}
//執(zhí)行結(jié)果
--- from example ---
??
??
??
??
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create
創(chuàng)建一個(gè)自定義Observable
example("create") {
let disposeBag = DisposeBag()
let myJust = { (element: String) -> Observable<String> in
return Observable.create { observer in
observer.on(.next(element))
observer.on(.completed)
return Disposables.create()
}
}
myJust("??")
.subscribe { print($0) }
.disposed(by: disposeBag)
}
//執(zhí)行結(jié)果:
--- create example ---
next(??)
completed
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error
創(chuàng)建一個(gè)只發(fā)送error事件的Observable
example("error") {
let disposeBag = DisposeBag()
Observable<Int>.error(TestError.test)
.subscribe { print($0) }
.disposed(by: disposeBag)
}
//執(zhí)行結(jié)果:
--- error example ---
error(test)
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Subject
Subject可以訂閱別的Observable,也可以被訂閱并給它的訂閱者發(fā)送事件
常用:
PublishSubjectReplaySubjectBehaviorSubjectVariable
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PublishSubject
它的訂閱者只能接收到訂閱后發(fā)送的事件,無(wú)法接收到訂閱之前的事件
example("PublishSubject") {
let disposeBag = DisposeBag()
let subject = PublishSubject<String>()
subject.addObserver("1").disposed(by: disposeBag)
subject.onNext("??")
subject.onNext("??")
subject.addObserver("2").disposed(by: disposeBag)
subject.onNext("???")
subject.onNext("???")
}
//執(zhí)行結(jié)果:
--- PublishSubject example ---
Subscription: 1 Event: next(??)
Subscription: 1 Event: next(??)
Subscription: 1 Event: next(???)
Subscription: 2 Event: next(???)
Subscription: 1 Event: next(???)
Subscription: 2 Event: next(???)
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ReplaySubject
它的訂閱者定接收到訂閱之后發(fā)出的事件,并且能接收到訂閱之前的信號(hào),至于能接收到訂閱之前的多少個(gè)信號(hào)則由 bufferSize 參數(shù)決定
example("ReplaySubject") {
let disposeBag = DisposeBag()
let subject = ReplaySubject<String>.create(bufferSize: 1)
subject.addObserver("1").disposed(by: disposeBag)
subject.onNext("??")
subject.onNext("??")
subject.addObserver("2").disposed(by: disposeBag)
subject.onNext("???")
subject.onNext("???")
}
//執(zhí)行結(jié)果:
--- ReplaySubject example ---
Subscription: 1 Event: next(??)
Subscription: 1 Event: next(??)
Subscription: 2 Event: next(??)
Subscription: 1 Event: next(???)
Subscription: 2 Event: next(???)
Subscription: 1 Event: next(???)
Subscription: 2 Event: next(???)
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BehaviorSubject
它的訂閱者定接收到訂閱之后發(fā)出的事件,并且能接收到訂閱之前的前一個(gè)信號(hào)
example("BehaviorSubject") {
let disposeBag = DisposeBag()
let subject = BehaviorSubject(value: "??")
subject.addObserver("1").disposed(by: disposeBag)
subject.onNext("??")
subject.onNext("??")
subject.addObserver("2").disposed(by: disposeBag)
subject.onNext("???")
subject.onNext("???")
subject.addObserver("3").disposed(by: disposeBag)
subject.onNext("??")
subject.onNext("??")
}
//執(zhí)行結(jié)果:
--- BehaviorSubject example ---
Subscription: 1 Event: next(??)
Subscription: 1 Event: next(??)
Subscription: 1 Event: next(??)
Subscription: 2 Event: next(??)
Subscription: 1 Event: next(???)
Subscription: 2 Event: next(???)
Subscription: 1 Event: next(???)
Subscription: 2 Event: next(???)
Subscription: 3 Event: next(???)
Subscription: 1 Event: next(??)
Subscription: 2 Event: next(??)
Subscription: 3 Event: next(??)
Subscription: 1 Event: next(??)
Subscription: 2 Event: next(??)
Subscription: 3 Event: next(??)
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Variable
它的訂閱者定接收到訂閱之后發(fā)出的事件和訂閱之前的前一個(gè)信號(hào),并且當(dāng)它的 value 發(fā)生改變時(shí)所有的訂閱者能收到事件,完成后向所有訂閱者發(fā)送 complete 事件
example("Variable") {
let disposeBag = DisposeBag()
let variable = Variable("??")
variable.asObservable().addObserver("1").disposed(by: disposeBag)
variable.value = "??"
variable.value = "??"
variable.asObservable().addObserver("2").disposed(by: disposeBag)
variable.value = "???"
variable.value = "???"
}
//執(zhí)行結(jié)果:
--- Variable example ---
Subscription: 1 Event: next(??)
Subscription: 1 Event: next(??)
Subscription: 1 Event: next(??)
Subscription: 2 Event: next(??)
Subscription: 1 Event: next(???)
Subscription: 2 Event: next(???)
Subscription: 1 Event: next(???)
Subscription: 2 Event: next(???)
Subscription: 1 Event: completed
Subscription: 2 Event: completed
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組合操作
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startWith
這個(gè)不好描述,看代碼,別說(shuō)話,用心去感受
example("startWith") {
let disposeBag = DisposeBag()
Observable.of("??", "??", "??", "??")
.startWith("1")
.startWith("2")
.startWith("3", "???", "???")
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
}
//執(zhí)行結(jié)果:
--- startWith example ---
3
???
???
2
1
??
??
??
??
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merge
把兩個(gè)隊(duì)列按照順序組合在一起
example("merge") {
let disposeBag = DisposeBag()
let subject1 = PublishSubject<String>()
let subject2 = PublishSubject<String>()
Observable.of(subject1, subject2)
.merge()
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
subject1.onNext("???")
subject1.onNext("???")
subject2.onNext("①")
subject2.onNext("②")
subject1.onNext("??")
subject2.onNext("③")
}
//執(zhí)行結(jié)果:
--- merge example ---
???
???
①
②
??
③
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zip
將多個(gè)序列組合在一起,當(dāng)所有序列能湊成一組(一一對(duì)應(yīng))時(shí)才發(fā)送事件
example("zip") {
let disposeBag = DisposeBag()
let stringSubject = PublishSubject<String>()
let intSubject = PublishSubject<Int>()
Observable.zip(stringSubject, intSubject) { stringElement, intElement in
"\(stringElement) \(intElement)"
}
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
stringSubject.onNext("???")
stringSubject.onNext("???")
intSubject.onNext(1)
intSubject.onNext(2)
stringSubject.onNext("??")
intSubject.onNext(3)
}
//執(zhí)行結(jié)果:
--- zip example ---
??? 1
??? 2
?? 3
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combineLatest
多個(gè)序列合并,每個(gè)序列的最新值進(jìn)行組合
example("combineLatest") {
let disposeBag = DisposeBag()
let stringSubject = PublishSubject<String>()
let intSubject = PublishSubject<Int>()
Observable.combineLatest(stringSubject, intSubject) { stringElement, intElement in
"\(stringElement) \(intElement)"
}
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
stringSubject.onNext("???")
stringSubject.onNext("???")
intSubject.onNext(1)
intSubject.onNext(2)
stringSubject.onNext("??")
}
//執(zhí)行結(jié)果:
--- combineLatest example ---
??? 1
??? 2
?? 2
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轉(zhuǎn)換操作
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map
對(duì)序列的值做轉(zhuǎn)換操作后返回,序列的值發(fā)生改變
example("map") {
let disposeBag = DisposeBag()
Observable.of(1, 2, 3)
.map { $0 * $0 } //1*1 2*2 3*3
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
}
//執(zhí)行結(jié)果:
--- map example ---
1
4
9
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flatMap and flatMapLatest
看代碼
example("flatMap and flatMapLatest") {
let disposeBag = DisposeBag()
struct Player {
var score: Variable<Int>
}
let ???? = Player(score: Variable(80))
let ???? = Player(score: Variable(90))
let player = Variable(????)
player.asObservable()
.flatMap { $0.score.asObservable() } // Change flatMap to flatMapLatest and observe change in printed output
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
????.score.value = 85
player.value = ????
????.score.value = 95 // Will be printed when using flatMap, but will not be printed when using flatMapLatest
????.score.value = 100
}
//執(zhí)行結(jié)果:
--- flatMap and flatMapLatest example ---
80
85
90
95
100
