How to use RxSwift Observable<Int>.interval?

Question

I'm trying to emit a sequence on a ”pulse” at a given time interval. Totally new to everything Rx, but thought this would do it:

import RxSwift
let db = DisposeBag()

_ = Observable<Int>.interval(1.0, scheduler: MainScheduler.instance)
    .debug("interval")
    .subscribe(onNext: {
        print($0)
    })
    .addDisposableTo(db)

But it only outputs:

2017-09-25 06:12:41.161: interval -> subscribed

And nothing more. What am I not understanding here?

What's a lifetime of your dispose bag - db? Try again without this line: .addDisposableTo(db) — Nikita Ermolenko
Tried it now. With or without .addDisposable it stil doesn't seem to emit anything. I've added the complete code in my playground now. The dispose bag should be alive. — PEZ
I think it is latest, I have this in my Podfile: pod 'RxSwift', '~> 3.0' — PEZ

iska iska · Accepted Answer · 2017-09-25T17:24:11

There is nothing wrong with your code. The dispose bag is alive as it should be. However, the playground execution ends as soon as the last instruction is run, hence the problem.

In order to tell the playground to continue running after everything was executed, you have to import PlaygroundSupport and tell the page to continue running:

import RxSwift
import PlaygroundSupport

let db = DisposeBag()

Observable<Int>.interval(1.0, scheduler: MainScheduler.instance)
    .debug("interval")
    .subscribe(onNext: {
        print($0)
    })
    .addDisposableTo(db)

PlaygroundPage.current.needsIndefiniteExecution = true

How to use RxSwift Observable<Int>.interval?

1 Answers