Skip to content

zouquan741/RxSwift-Questions

BranchesTags
 
 

Folders and files

NameName
Last commit message
Last commit date

Latest commit

 

History

21 Commits
README.md
README.md
 
 
RxOperator.png
RxOperator.png
 
 

Repository files navigation

List Of RxSwift Questions

1. 用哪个操作符可以模拟promise的then

  • A: compactMap
  • B: publish
  • C: flatMap
  • D: withLatestFrom

2. 如果要旁路一个Observable的事件，应该用什么操作符

  • A: do
  • B: share
  • C: repeatElement
  • D: amb

3. 为防止按钮点击太频繁，在指定时间内点击多次也只触发一次，应该用哪个操作符？

  • A: buffer
  • B: window
  • C: debounce
  • D: throttle

4. 如下哪个操作符，传入多个Observables后，只取第一个产生事件的Observable，忽略其他Observables？

  • A: amb
  • B: buffer
  • C: filter
  • D: map

5. 如下哪个操作符，缓存元素，然后将缓存的元素集合周期性的发？

  • A: amb
  • B: buffer
  • C: filter
  • D: timer

6. 关于catchError描述错误的是

  • A: 从一个错误事件中恢复，将错误事件替换成一个备选序列
  • B: 拦截一个 error 事件，将它替换成其他的元素或者一组元素
  • C: 具备重试的能力
  • D: 可以使得 Observable 正常结束，或者根本都不需要结束

7. 有事件A与B，只有当A触发的时候B的订阅者才能收到之后的一个元素，可以用哪个操作符实现

  • A: takeUntil
  • B: withLatestFrom
  • C: skipUntil
  • D: skipWhile

8. 信号A依次输出1、2、3，信号B依次输出X、Y、Z，想要得到X、1、Y、2、3、Z，可以使用什么命令

  • A: combineLatest
  • B: zip
  • C: merge
  • D: startWith

9. 关于ConcatMap与FlatMap，以下说法正确的是？

  • A: ConcatMap可以将所有子 Observables 的元素发送出来
  • B: FlatMap打印Observables的元素是按子Observables先后顺序依次打印的
  • C: FlatMap过程会将每一个元素转换成Observables
  • D: ConcatMap能够立即处理新的子Observables的订阅

10. 以下关于ControlEvent、ControlProperty的说法不正确的是？

  • A: 一定在 MainScheduler 订阅
  • B: 一定在 MainScheduler 监听
  • C: 没有共享附加作用
  • D: 不会产生 error 事件

11. 以下关于操作符的说法不正确的是

  • A: flatMapLatest是map和switchLatest操作符的组合
  • B: 可以用withLatestFrom加distinctUntilChanged实现sample操作符
  • C: amb命令只处理最先接收到的next事件的数据源，其他全部忽略
  • D: 在指定时间内没有发任何出元素，timeout操作符会产生一个超时的error事件

12. 如果想让订阅代码在指定线程执行，需要用哪个操作符

  • A: subscribeOn
  • B: obseverOn
  • C: materialize
  • D: using

13. 如果Observable被多次订阅，但只希望执行一次创建代码，下面哪种方式是可以的

  • A: Single对象
  • B: publish操作符
  • C: refCount操作符
  • D: buffer操作符

14. 下面哪个对象跟其它三个差别较大

  • A: Single
  • B: Signal
  • C: Driver
  • D: ControlEvent

15. 下面哪个对象不属于 Observable & Observer

  • A: PublishRelay
  • B: ControlEvent
  • C: ControlProperty
  • D: BehaviorSubject

16. 下面哪个操作符也可以不需要手动调用complete/error也可以清理Rx的资源

  • A: skipWhile
  • B: takeUntil
  • C: sample
  • D: refCount

17. 哪个操作符可将connectable的对象转为普通observable对象

  • A: refCount
  • B: publish
  • C: sample
  • D: replay

18. 如下代码执行结果是？

let o = Observable.from([1,2,3]).publish()
_ = o.subscribe(onNext: { print($0) })
_ = o.subscribe(onNext: { print($0) })
_ = o.connect()
_ = o.subscribe(onNext: { print($0) })
  • A: 1 2 3 1 2 3 1 2 3
  • B: 1 2 3 1 2 3
  • C: 1 1 2 2 3 3
  • D: 1 1 2 2 3 3 1 2 3

19. 如下代码执行结果是？

let o = Observable.from([1,2,3]).replay(2)
_ = o.subscribe(onNext: { print($0) })
_ = o.subscribe(onNext: { print($0) })
_ = o.connect()
_ = o.subscribe(onNext: { print($0) })
_ = o.connect()
  • A: 1 1 2 2 3 3 1 2 3
  • B: 1 1 2 2 3 3 2 3
  • C: 1 1 2 2 3 3 1 1 1 2 2 2 3 3 3
  • D: 1 1 2 2 3 3 2 3 1 1 1 2 2 2 3 3 3

20. 如下代码执行结果是？

let o = Observable.from([1,2,3]).share(replay: 2)
_ = o.subscribe(onNext: { print($0) })
_ = o.subscribe(onNext: { print($0) })
_ = o.subscribe(onNext: { print($0) })
  • A: 1 2 3 1 2 3 1 2 3
  • B: 1 2 3 2 3 2 3
  • C: 2 3 2 3 2 3
  • D: 1 1 1 2 2 2 3 3 3

21. 如下代码执行结果是什么样的？

let o = Observable.from([1,2,3]).share(replay: 1, scope: .forever)
_ = o.subscribe(onNext: { print($0) })
_ = o.subscribe(onNext: { print($0) })
_ = o.subscribe(onNext: { print($0) })
  • A: 1 2 3 1 2 3 1 2 3
  • B: 1 2 3 3 3
  • C: 3 3 3
  • D: 1 1 1 2 2 2 3 3 3

22. 如下代码执行结果是？

let o = Observable<Int>.interval(.seconds(1), scheduler: MainScheduler.instance)
  .take(3)
  .share(replay: 2)
_ = o.subscribe(onNext: { print($0) })
_ = o.subscribe(onNext: { print($0) })
  • A: 0 1 2 0 1 2 0 1 2
  • B: 0 1 2 1 2 1 2
  • C: 1 2 1 2 1 2
  • D: 0 0 1 1 2 2

23. 如下代码执行结果是？

let o = Observable.from([1,2]).share(replay: 1, scope: .forever)
let d1 = o.subscribe(onNext: { print($0) })
d1.dispose()
_ = o.subscribe(onNext: { print($0) })
let o = Observable.from([1,2]).concat(Observable.never()).share(replay: 1, scope: .forever)
let d1 = o.subscribe(onNext: { print($0) })
d1.dispose()
_ = o.subscribe(onNext: { print($0) })
  • A: 1 2 2 1 2 和 1 2 2
  • B: 1 2 2 1 2 和 1 2 2 1 2
  • C: 1 2 2 和 1 2 2
  • D: 1 2 2 和 1 2 2 1 2

24. 如下代码执行结果是？

let s = PublishSubject<Int>()
let t = s.throttle(.seconds(2), scheduler: MainScheduler.instance)
let d = s.debounce(.seconds(2), scheduler: MainScheduler.instance)
_ = d.subscribe(onNext: { print("b" + String($0)) })
_ = t.subscribe(onNext: { print("a" + String($0)) })
s.onNext(1)
_ = Observable<Never>.empty().delay(.seconds(1), scheduler: MainScheduler.instance).subscribe {
    s.onNext(2)
}
  • A: b1 b2 a2
  • B: a1 a2 b2
  • C: a1 b1 a2 b2
  • D: a1 b2 a2

25. 如下代码执行结果是？

let o = Observable.from(1...10).groupBy { $0 % 3 }.flatMap { $0.toArray() }
_ = o.subscribe(onNext: { print($0) })
  • A: [1, 4, 7, 10]
  • B: [1, 2, 3]、[4, 5, 6] 和 [7, 8, 9]
  • C: [1, 4, 7, 10]、[2, 5, 8] 和 [3, 6, 9]
  • D: [1, 2, 3]、[4, 5, 6]、[7, 8, 9] 和 [10]

26. 如下代码执行结果是？

let o = Observable.from(1...10).groupBy { $0 % 3 }.concatMap { $0 }
_ = o.subscribe(onNext: { print($0) })
  • A: 1 4 7 10
  • B: 1 2 3 4 5 6 7 8 9
  • C: 1 4 7 10 2 5 8 3 6 9
  • D: 1 2 3 4 5 6 7 8 9 10

27. 如下代码执行结果是？

let o = Observable.from(1...10).groupBy { $0 % 3 }.flatMap { $0 }
_ = o.subscribe(onNext: { print($0) })
  • A: 1 4 7 10
  • B: 1 2 3 4 5 6 7 8 9
  • C: 1 4 7 10 2 5 8 3 6 9
  • D: 1 2 3 4 5 6 7 8 9 10

28. 如下代码执行结果是？

let o1 = Observable.interval(.seconds(1), scheduler: MainScheduler.instance).map{ String(UnicodeScalar(UInt8($0 + 97))) }.take(3)
let o2 = Observable<Int>.interval(.milliseconds(700), scheduler: MainScheduler.instance).take(4)
_ = Observable.combineLatest(o1, o2) { $0 + String($1) }.subscribe(onNext: { print($0) })
  • A: a0 b1 c2
  • B: a0 a1 b1 b2 c2 c3
  • C: a0 a1 b1 b2 b3 c3
  • D: a0 b1 c2 c3

29. 如下代码执行结果是？

var error = true
_ = Observable.of(1, 2, 3, 4).flatMap { v -> Observable<Int> in
    if v == 2, error {
        error = false
        return Observable.error(TestError())
    }
    return Observable.of(v)
}.materialize()
.filter { $0.error == nil }
.dematerialize()
.retry()
.subscribe(onNext: { r in
    print(r)
})
  • A: 1 2 3 4
  • B: 1 2 1 2 3 4
  • C: 1 1 2 3 4
  • D: 1

30. 如下代码执行结果是？

let one = PublishSubject<String>()
let two = PublishSubject<String>()

let source = PublishSubject<Observable<String>>()
source.switchLatest().subscribe(onNext: { value in
    print(value)
})

one.onNext("1")
source.onNext(one)

two.onNext("X")
source.onNext(two)

one.onNext("2")
two.onNext("Y")
source.onNext(one)

one.onNext("3")
  • A: 1 X Y
  • B: 1 Y 3
  • C: Y 3
  • D: 1 X 2 Y

31. 如下代码执行结果是什么样的？

let ob = Observable<Int>.from([1, 2]).publish()
ob.subscribe(onNext: { _ in
    print("X")
})
ob.subscribe(onNext: { _ in
    print("Y")
})
ob.connect()
ob.subscribe(onNext: { _ in
    print("Z")
})
  • A: X Y X Y
  • B: X Y X Y
  • C: X Y Z X Y Z
  • D: X X Y Y Z Z

32. 如下代码执行结果是什么样的？

let pbSubject = PublishSubject<Int>()
_ = pbSubject.debounce(.seconds(1), scheduler: MainScheduler.instance)
    .subscribe(onNext: { print("d", $0) })

_ = pbSubject.throttle(.seconds(1), scheduler: MainScheduler.instance)
    .subscribe(onNext: { print("t", $0) })

pbSubject.onNext(1)
pbSubject.onNext(2)
pbSubject.onNext(3)
  • A: d1 d3 t3
  • B: t1 t3 d3
  • C: t1 d3 t3
  • D: d3 t1

33. 如下代码执行结果是什么样的？

let button = PublishSubject<Void>()
let textField = PublishSubject<String>()
button.withLatestFrom(textField).subscribe(onNext: { value in
    print(value)
})

textField.onNext("A")
textField.onNext("B")
textField.onNext("C")
button.onNext(())
button.onNext(())
  • A: A B C C C
  • B: A A A B C
  • C: C
  • D: C C

34. 如下代码执行结果是？

var error = true
_ = Observable.of(1, 2, 3, 4).flatMap { v -> Observable<Int> in
    if v == 2, error {
        error = false
        return Observable.error(TestError.test)
    }
    return Observable.of(v)
}.retry()
.subscribe(onNext: { print($0) })
  • A: 1 2 3 4
  • B: 1 2 1 2 3 4
  • C: 1 1 2 3 4
  • D: 1 2 3 4 1 2 3 4

35. 如下代码执行结果是？

let first: Single<Int> = Single.create { observer -> Disposable in
    observer(.success(1))
    observer(.success(2))
    return Disposables.create()
}

let second: Observable<Int> = Observable.create { observer -> Disposable in
    observer.onNext(3)
    observer.onNext(4)
    return Disposables.create()
}

_ = first.subscribe({ print($0) })
_ = first
    .asObservable()
    .single()
    .subscribe({ print($0) })

_ = second.subscribe({ print($0) })
_ = second
    .single()
    .subscribe({ print($0) })
  • A: error, next(1), error, next(3), next(4), next(3), error
  • B: error, next(1), completed, next(3), next(4), next(3), error
  • C: success(1), next(1), completed, next(3), next(4), next(3), completed
  • D: success(1), next(1), completed, next(3), next(4), next(3), error

36. 如下代码执行结果是？

let subject = BehaviorSubject(value: 1)
let observable = subject.asObserver().debug("O").publish().refCount()

subject.onNext(2)

var subscriptions = [
    observable.debug("A").subscribe(onNext: { print("A\($0)") }),
    observable.debug("B").subscribe(onNext: { print("B\($0)") }),
]

subject.onNext(3)

subscriptions.popLast()?.dispose()

subject.onNext(4)

subscriptions.popLast()?.dispose()

subject.onNext(5)

subscriptions.append(observable.subscribe(onNext: { print("C\($0)") }))

subject.onNext(6)
  • A: A2 B2 A3 B3 A4 C5 C6
  • B: A2 B2 A3 B3 A4 C6
  • C: A2 A3 B3 A4 C5 C6
  • D: B3 A3 B3 A4 C5 C6

37. 如下代码执行结果是？

let first = PublishSubject<Int>()
let second = PublishSubject<Int>()

first.catchError({ _ in return second.catchErrorJustReturn(0) })
    .subscribe({ print($0) })
    .disposed(by: disposeBag)

first.onNext(1)
second.onNext(2)
first.onError(QuizError())
second.onNext(3)
first.onNext(4)
first.onError(QuizError())
second.onNext(5)
second.onError(QuizError())
second.onNext(6)
  • A: next(1) error next(3) next(5) next(0) next(6)
  • B: next(1) error next(3) next(5) next(0) completed
  • C: next(1) next(3) next(5) next(0) next(6)
  • D: next(1) next(3) next(5) next(0) completed

38. 如下代码执行结果是？

let first = Observable<Int>.interval(.milliseconds(200), scheduler: MainScheduler.instance)
let second = Observable<Int>.interval(.milliseconds(200), scheduler: MainScheduler.instance)

_ = first
    .throttle(.milliseconds(100), scheduler: MainScheduler.instance)
    .debounce(.milliseconds(500), scheduler: MainScheduler.instance)
    .subscribe(onNext: { print("A\($0)") })
_ = second
    .debounce(.milliseconds(100), scheduler: MainScheduler.instance)
    .throttle(.milliseconds(500), scheduler: MainScheduler.instance)
    .subscribe(onNext: { print("B\($0)") })
  • A: A0 B0 A2 B2 A5 B5 A7 B7...
  • B: B0 B2 B5 B7 B10...
  • C: A0 A2 A5 A7 A10...
  • D: (NOTHING OUTPUT)

39. 如下代码执行结果是？

let first = BehaviorSubject(value: 1)
let second = BehaviorSubject(value: 1)

_ = first
    .asObserver().debug("A")
    .delay(.milliseconds(200), scheduler: MainScheduler.instance)
    .delaySubscription(.milliseconds(100), scheduler: MainScheduler.instance)
    .subscribe(onNext: { print("A\($0)") })

_ = second
    .asObserver().debug("B")
    .delaySubscription(.milliseconds(200), scheduler: MainScheduler.instance)
    .delay(.milliseconds(100), scheduler: MainScheduler.instance)
    .subscribe(onNext: { print("B\($0)") })

first.onNext(2)
second.onNext(2)
  • A: A1 A2 B1 B2
  • B: A1 A2 B2
  • C: B2 A2
  • D: A2 B2

40. 如下代码执行结果是？

let first = PublishSubject<Int>()
let second = PublishSubject<Int>()
let third = PublishSubject<Int>()

_ = Observable<Int>
    .amb([first.asObservable(), second.asObservable()])
    .catchError({ _ in third.asObservable()})
    .subscribe{ print($0) }

first.onError(QuizError())
second.onNext(2)
third.onNext(3)

second.onError(QuizError())
third.onNext(4)
  • A: next(2) error
  • B: next(2) next(3) next(4)
  • C: next(3) next(4)
  • D: next(3) error

41. 如下代码执行结果是？

let first = PublishSubject<Int>()
let second = PublishSubject<Int>()
_ = first
    .asObservable()
    .timeout(.milliseconds(200), scheduler: MainScheduler.instance)
    .delay(.milliseconds(400), scheduler: MainScheduler.instance)
    .catchError({ _ in return Observable.empty()})
    .ifEmpty(switchTo: second)
    .subscribe({ print($0) })

first.onNext(1)
second.onNext(2)
  • A: next(1)
  • B: next(2)
  • C: next(1) next(2)
  • D: (NOTHING OUTPUT)

42. 如下代码执行结果是？

let first = PublishSubject<Int>()
let second = PublishSubject<Int>()
_ = first
    .asObservable()
    .timeout(.milliseconds(200), scheduler: MainScheduler.instance)
    .delay(.milliseconds(400), scheduler: MainScheduler.instance)
    .catchError({ _ in return Observable.empty()})
    .ifEmpty(switchTo: second)
    .subscribe({ print($0) })

first.onNext(1)
second.onNext(2)
first.onCompleted()
  • A: next(1)
  • B: next(2)
  • C: next(1) next(2)
  • D: (NOTHING OUTPUT)

About

RxSwift进阶问题

Resources

Readme
Activity

Stars

0 stars

Watchers

0 watching

Forks

0 forks
Report repository

Releases

No releases published

Packages

No packages published