本文是示例主要來自於官方的例項程式碼，可從這裡下載 ，例項程式碼稍有改動。其中的圖片來自於reactivex.io/

本文主要的作用是檢視例項程式碼並檢視對應例項程式碼的效果，不需要執行專案

操作符目錄

• RxSwift官方使用示例之<建立和訂閱Observables>
  • never、empty、just、of、from、create、range、repeatElement、generate、deferred、error、doOn
• RxSwift官方使用示例之<使用Subjects>
  • PublishSubject、ReplaySubject、BehaviorSubject
• RxSwift官方使用示例之<組合操作符>
  • startWith、merge、zip、combineLatest、Array.combineLatest、switchLatest、withLatestFrom
• RxSwift官方使用示例之<轉換操作符>
  • map、flatMap 和 flatMapLatest、scan
• RxSwift官方使用示例之<過濾及條件操作符>
  • filter、distinctUntilChanged、elementAt、single、take、takeLast、takeWhile、takeUntil、skip、skipWhile、skipWhileWithIndex、skipUntil
• RxSwift官方使用示例之<數學和聚合操作符>
  • toArray、reduce、concat
• RxSwift官方使用示例之<可連線操作符>
  • interval、publish、replay、multicast
• RxSwift官方使用示例之<錯誤處理操作符>
  • catchAndReturn、catchError、retry、retry(_:)

debug 操作符會列印所有的 subscriptions, events, disposals

公用程式碼，之後的程式碼中會用到

public func delay(_ delay: Double, closure: @escaping () -> Void) { DispatchQueue.main.asyncAfter(deadline: .now() + delay) { closure() } }

interval

建立一個每隔一段時間傳送元素的Observable序列 let interval = Observable<Int>.interval(.seconds(1), scheduler: MainScheduler.instance) _ = interval .subscribe(onNext: { print("Subscription: 1, Event: \($0)") }) delay(2) { _ = interval .subscribe(onNext: { print("Subscription: 2, Event: \($0)") }) } 列印

Subscription: 1, Event: 0 Subscription: 1, Event: 1 Subscription: 1, Event: 2 Subscription: 2, Event: 0 Subscription: 1, Event: 3 Subscription: 2, Event: 1 Subscription: 1, Event: 4

注意第2個訂閱者收到事件是在第2秒，並且是從0開始計數

publish

把源Observable序列轉換成一個可連線（contactable）序列

有圖可知，publish 的序列在 connect 之後，會對訂閱者傳送資料，並且是傳送訂閱後序列產生的新資料 ``` let intSequence = Observable.interval(.seconds(1), scheduler: MainScheduler.instance) .publish() // 轉為可連線序列

_ = intSequence .subscribe(onNext: { print("Subscription 1:, Event: ($0)") })

delay(2) { _ = intSequence.connect() } // 開始連線，連線之後下一秒開始對已訂閱者 Subscription 1 傳送資料

delay(4) { _ = intSequence .subscribe(onNext: { print("Subscription 2:, Event: ($0)") }) }

delay(6) { _ = intSequence .subscribe(onNext: { print("Subscription 3:, Event: ($0)") }) } ``` 列印

Subscription 1:, Event: 0 Subscription 1:, Event: 1 Subscription 2:, Event: 1 Subscription 1:, Event: 2 Subscription 2:, Event: 2 Subscription 1:, Event: 3 Subscription 2:, Event: 3 Subscription 3:, Event: 3 Subscription 1:, Event: 4 Subscription 2:, Event: 4 Subscription 3:, Event: 4 ...

replay

將源 Observable 序列轉換為可連線序列，並將重發之前傳送的 bufferSize 數量的元素給每個新訂閱者

``` let intSequence = Observable.interval(.seconds(1), scheduler: MainScheduler.instance) .replay(5) // 最多重發5個

_ = intSequence .subscribe(onNext: { print("Subscription 1:, Event: ($0)") })

delay(2) { _ = intSequence.connect() } // 開始連線，下一秒開始傳送資料

delay(4) { _ = intSequence .subscribe(onNext: { print("Subscription 2:, Event: ($0)") }) }

delay(8) { _ = intSequence .subscribe(onNext: { print("Subscription 3:, Event: ($0)") }) } `` 列印（// 之後是分析`）

Subscription 1:, Event: 0 // 第3秒列印 Subscription 2:, Event: 0 // 第4秒列印，先把快取的資料0給新訂閱者 Subscription 2 Subscription 1:, Event: 1 // 依次給訂閱者1、2傳送資料1 Subscription 2:, Event: 1 Subscription 1:, Event: 2 // 第5秒列印，給訂閱者1、2傳送資料2 Subscription 2:, Event: 2 Subscription 1:, Event: 3 // 第6秒列印，給訂閱者1、2傳送資料3 Subscription 2:, Event: 3 Subscription 1:, Event: 4 // 第7秒列印，給訂閱者1、2傳送資料4 Subscription 2:, Event: 4 Subscription 3:, Event: 0 // 第8秒列印，先把快取的資料 01234 給新訂閱者 Subscription 3 Subscription 3:, Event: 1 Subscription 3:, Event: 2 Subscription 3:, Event: 3 Subscription 3:, Event: 4 Subscription 1:, Event: 5 // 然後再給訂閱者1、2、3傳送資料5 Subscription 2:, Event: 5 Subscription 3:, Event: 5 Subscription 1:, Event: 6 // 第9秒列印，給訂閱者1、2、3傳送資料6 Subscription 2:, Event: 6 Subscription 3:, Event: 6 ...

multicast

將源 Observable 序列轉換為可連線序列，並通過指定訂閱者廣播資料

``` let subject = PublishSubject()

_ = subject .subscribe(onNext: { print("Subject: ($0)") })

let intSequence = Observable.interval(.seconds(1), scheduler: MainScheduler.instance) .multicast(subject) // 指定廣播的訂閱者

_ = intSequence .subscribe(onNext: { print("\tSubscription 1:, Event: ($0)") })

delay(2) { _ = intSequence.connect() }

delay(4) { _ = intSequence .subscribe(onNext: { print("\tSubscription 2:, Event: ($0)") }) }

delay(6) { _ = intSequence .subscribe(onNext: { print("\tSubscription 3:, Event: ($0)") }) } ``` 列印

Subject: 0 Subscription 1:, Event: 0 Subject: 1 Subscription 1:, Event: 1 Subscription 2:, Event: 1 Subject: 2 Subscription 1:, Event: 2 Subscription 2:, Event: 2 Subject: 3 Subscription 1:, Event: 3 Subscription 2:, Event: 3 Subscription 3:, Event: 3 ...