本文是示例首要来自于官方的实例代码，可从这儿下载 ，实例代码稍有改动。其中的图片来自于reactivex.io/

本文首要的作用是检查实例代码并检查对应实例代码的作用，不需要运转项目

操作符目录

• RxSwift官方运用示例之<创建和订阅Observables>
  • never、empty、just、of、from、create、range、repeatElement、generate、deferred、error、doOn
• RxSwift官方运用示例之<运用Subjects>
  • PublishSubject、ReplaySubject、BehaviorSubject
• RxSwift官方运用示例之<组合操作符>
  • startWith、merge、zip、combineLatest、Array.combineLatest、switchLatest、withLatestFrom
• RxSwift官方运用示例之<转换操作符>
  • map、flatMap 和 flatMapLatest、scan
• RxSwift官方运用示例之<过滤及条件操作符>
  • filter、distinctUntilChanged、elementAt、single、take、takeLast、takeWhile、takeUntil、skip、skipWhile、skipWhileWithIndex、skipUntil
• RxSwift官方运用示例之<数学和聚合操作符>
  • toArray、reduce、concat
• RxSwift官方运用示例之<可衔接操作符>
  • interval、publish、replay、multicast
• RxSwift官方运用示例之<错误处理操作符>
  • catchAndReturn、catchError、retry、retry(_:)

debug 操作符会打印一切的 subscriptions, events, disposals

filter

只宣布 Observable 序列中满意指定条件的元素

let disposeBag = DisposeBag()
Observable.of(2, 30, 22, 5, 60, 1)
    .filter {
        $0 > 10
    }
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)

打印

30
22
60

distinctUntilChanged

抑制由 Observable 序列宣布的接连重复元素

let disposeBag = DisposeBag()
Observable.of(1, 2, 2, 1, 3)
    .distinctUntilChanged()
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)

打印

1
2
1
3

elementAt

只发射 Observable 序列指定索引处的元素

let disposeBag = DisposeBag()
Observable.of(1, 2, 3, 4)
    .element(at: 2)
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)

打印

3

single

仅发射 Observable 序列发射的第一个元素（或第一个满意条件的元素）。 假如 Observable 序列没有宣布恰好一个元素，则会抛犯错误

let disposeBag = DisposeBag()
Observable.of("", "", "", "", "", "")
    .single()
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)

打印

Unhandled error happened: Sequence contains more than one element.

此刻会有错误信息打印，假如想处理该错误信息，能够加上 onError:，如下

let disposeBag = DisposeBag()
Observable.of("", "", "", "", "", "")
    .single()
    .subscribe(onNext: { print($0) }, onError: { print("犯错啦：", $0) } )
    .disposed(by: disposeBag)

打印

犯错啦： Sequence contains more than one element.

此外，single 还能够加上条件判别

let disposeBag = DisposeBag()
Observable.of("", "", "", "", "", "")
    .single { $0 == "" }
    .subscribe { print($0) }
    .disposed(by: disposeBag)
Observable.of("", "", "", "", "", "")
    .single { $0 == "" }
    .subscribe { print($0) }
    .disposed(by: disposeBag)
Observable.of("", "", "", "", "", "")
    .single { $0 == "" }
    .subscribe { print($0) }
    .disposed(by: disposeBag)

打印

next()
completed
next()
error(Sequence contains more than one element.)
error(Sequence doesn't contain any elements.)

从打印能够看出，第一个打印正常，输出一个结果之后当即completed；第二个打印反常，由于有2个，所以抛出反常 error(Sequence contains more than one element.)；第三个也反常，由于序列中没有，抛出反常error(Sequence doesn’t contain any elements.)

take

仅从 Observable 序列的最初宣布指定数量的元素

let disposeBag = DisposeBag()
Observable.of(1, 2, 3, 4)
    .take(2)
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)

打印

1
2

takeLast

仅从 Observable 序列的末尾宣布指定数量的元素

let disposeBag = DisposeBag()
Observable.of(1, 2, 3, 4)
    .take(1)
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)

打印

4

takeWhile

从 Observable 序列的最初宣布满意条件的元素

let disposeBag = DisposeBag()
Observable.of(1, 2, 3, 4, 5, 6)
    .take(while: { $0 < 4 } )
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)

打印

1
2
3

takeUntil

从源 Observable 序列中宣布元素，直到引用 Observable 序列宣布元素

let disposeBag = DisposeBag()
let sourceSequence = PublishSubject<String>()
let referenceSequence = PublishSubject<String>()
sourceSequence
    .take(until: referenceSequence)
    .subscribe { print($0) }
    .disposed(by: disposeBag)
sourceSequence.onNext("1")
sourceSequence.onNext("2")
sourceSequence.onNext("3")
sourceSequence.onNext("3")
sourceSequence.onNext("4")
sourceSequence.onNext("5")
referenceSequence.onNext("0")
sourceSequence.onNext("6")
sourceSequence.onNext("7")
sourceSequence.onNext("8")
referenceSequence.onNext("0")
sourceSequence.onNext("9")

打印

next(1)
next(2)
next(3)
next(3)
next(4)
next(5)
completed

skip

从 Observable 序列的最初越过发射指定数量的元素

let disposeBag = DisposeBag()
Observable.of(1, 2, 3, 4)
    .skip(2)
    .subscribe { print($0) }
    .disposed(by: disposeBag)

打印

next(3)
next(4)
completed

skipWhile

从 Observable 序列的最初越过发射满意条件的元素

let disposeBag = DisposeBag()
Observable.of(1, 2, 3, 4, 5, 6)
    .skip(while: { $0 < 4 } )
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)

打印

4
5
6

skipWhileWithIndex

从 Observable 序列的最初越过发射满意条件的元素

这不便是 skipWhile 操作符吗，不过是带索引的skip

let disposeBag = DisposeBag()
Observable.of("", "", "", "", "", "")
    .enumerated()
    .skip(while: { $0.index < 3 } )
    .subscribe(onNext: { print($0) } )
    .disposed(by: disposeBag)

打印

(index: 3, element: "")
(index: 4, element: "")
(index: 5, element: "")

skipUntil

越过从源 Observable 序列中发射元素，直到引用 Observable 序列发射一个元素。

let disposeBag = DisposeBag()
let sourceSequence = PublishSubject<String>()
let referenceSequence = PublishSubject<String>()
sourceSequence
    .skip(until: referenceSequence)
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)
sourceSequence.onNext("1")
sourceSequence.onNext("2")
sourceSequence.onNext("3")
sourceSequence.onNext("4")
sourceSequence.onNext("5")
referenceSequence.onNext("0")
sourceSequence.onNext("6")
sourceSequence.onNext("7")
sourceSequence.onNext("8")
referenceSequence.onNext("0")
sourceSequence.onNext("9")

打印

6
7
8
9