Run and Pause an ARSession in a specified period of time

I'm developing ARKit/Vision iOS app with gesture recognition. My app has a simple UI containing single UIView. There's no ARSCNView/ARSKView at all. I'm putting a sequence of captured ARFrames into CVPixelBuffer what then I use for VNRecognizedObjectObservation.

I don't need any tracking data from a session. I just need currentFrame.capturedImage for CVPixelBuffer. And I need to capture ARFrames at 30 fps. 60 fps is excessive frame rate.

preferredFramesPerSecond instance property is absolutely useless in my case, because it controls frame rate for rendering an ARSCNView/ARSKView. I have no ARViews.

So, I decided to use run() and pause() methods to decrease a session's frame rate.

Question

I'd like to know how to automatically run and pause an ARSession in a specified period of time? The duration of run and pause methods must be 16 ms (or 0.016 sec). I suppose it might be possible through DispatchQueue. But I don't know how to implement it.

How to do it?

Here's a pseudo-code:

session.run(configuration)

    /*  run lasts 16 ms  */

session.pause()

    /*  pause lasts 16 ms  */

session.run(session.configuration!)

    /*  etc...  */

P.S. I can't use any CocoaPods or Carthage in my app.

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