Timer.publish on non main Thread

Question

When executing the below code, is it possible to publish timer events on non main thread.

How do I make it publish on non main thread?

let timer = Timer.publish(every: 1, on: .main, in: common).autoconnect()


timer
.sink {
.......
}

Receive on could help, right?

for example:

let timerQueue = DispatchQueue.global(qos: .utility)
timer
.receive(on: queue)
.sink {
.......
}

Is this the only way or initialization of Timer.publish can handle it (not sure if we can pass a parameter to Timer.publish to dispatch the timer events on non main thread)?

Answer 1

If your goal is simply to run a timer on a thread other than the main thread then this code should work:

import UIKit
import Combine
import PlaygroundSupport

var saveCancellable: AnyCancellable?

let myThread = Thread {
  let runLoop = RunLoop.current
  saveCancellable = Timer.publish(every: 1.0, on: runLoop, in: .common)
    .autoconnect()
    .sink  { _ in
      debugPrint(Thread.current)
    }


  print("Run the run loop")
  runLoop.run()
}
myThread.start()

PlaygroundSupport.PlaygroundPage.current.needsIndefiniteExecution = true

It's a playground so you can copy and paste it and play with the code.

Basically this code creates a Thread and then creates a RunLoop on that thread (by calling RunLoop.current which implicitly causes the run loop to be created). I then sets up a timer that publishes on that run loop. Finally it starts the run loop running.