RxSwift: Repeat a (completed) stream - swift3

Question

Assume I have a button which can be used to start and stop (toggle) an action.
let toggleStream: Observable<Bool> = toggleBtn.rx.tap.scan(false) { state, _ in !state }
I have another stream, that emits Integers continuously.
let emitter = Observable<Int>.interval(2.0, scheduler: timerScheduler)
Now I want to use the toggle stream to start and stop the emitting of the second stream. This is my approach:
Observable.combineLatest(toggleStream, emitter) { shouldEmit, evt in
return (shouldEmit, evt)
}.takeWhile{ (shouldEmit, evt:Int) in
return shouldEmit == true
}.map {(_, evt) in
return evt
}
This works great for the first time. I can press the button and the Observable starts emitting its Ints. Also stopping works. Sadly I can't start it for a second time, because the stream is completed. How can I restart/retry/repeat it when the user toggles the button again?

Answer 1

Here's how I did it in the playground. You should be able to extrapolate:
//: Playground - noun: a place where people can play
import RxSwift
let toggleButton = PublishSubject<Void>()
let toggleStream: Observable<Bool> = toggleButton
.scan(false) { state, _ in !state }
.debug()
.shareReplayLatestWhileConnected()
let emit = toggleStream
.filter { $0 }
.flatMapLatest { _ in
Observable<Int>.interval(2.0, scheduler: MainScheduler.instance)
.takeUntil(toggleStream.filter { !$0 })
}
_ = emit.subscribe( {
print($0)
})
toggleButton.onNext()
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 5.0) {
toggleButton.onNext()
}
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 11.0) {
toggleButton.onNext()
}
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 17.0) {
toggleButton.onNext()
}
import PlaygroundSupport
PlaygroundPage.current.needsIndefiniteExecution = true