takeUntil

忽略掉在第二个 Observable 产生事件后发出的那部分元素

takeUntil - 图1

takeUntil 操作符将镜像源 Observable，它同时观测第二个 Observable。一旦第二个 Observable 发出一个元素或者产生一个终止事件，那个镜像的 Observable 将立即终止。

演示

  1. let disposeBag = DisposeBag()
  3. let sourceSequence = PublishSubject<String>()
  4. let referenceSequence = PublishSubject<String>()
  6. sourceSequence
  7.     .takeUntil(referenceSequence)
  8.     .subscribe { print($0) }
  9.     .disposed(by: disposeBag)
  11. sourceSequence.onNext("?")
  12. sourceSequence.onNext("?")
  13. sourceSequence.onNext("?")
  15. referenceSequence.onNext("?")
  17. sourceSequence.onNext("?")
  18. sourceSequence.onNext("?")
  19. sourceSequence.onNext("?")

输出结果：

  1. next(?)
  2. next(?)
  3. next(?)
  4. completed