functional-reactive-intuition-3-short.swift

let pan = UIPanGestureRecognizer()
let pinch = UIPinchGestureRecognizer()

let panStarted = pan.rx_event.filter { $0.state == .Began }
let panEnded = pan.rx_event.filter { $0.state == .Ended }

let pinchStarted = pinch.rx_event.filter { $0.state == .Began }
let pinchEnded = pinch.rx_event.filter { $0.state == .Ended }

// condition: when both pan and pinch ended
let bothGesturesEnded = Observable.of(panEnded, pinchEnded).merge()

// when both pan and pinch has begun, do this:
let _ = Observable.of(panStarted, pinchStarted).merge(maxConcurrent: 1).subscribeNext { _ in
  
  print("started")
  // create a timer that ticks every second, until 3 or until pan and pinch ended
  let timer = Observable<Int>.timer(repeatEvery: 1).take(3).takeUntil(bothGesturesEnded)

  timer.subscribe(onNext: { count in
    // when a tick happens, do this:
    print("tick: \(count)")
  }, onCompleted: {
    // when the timer completes, do this:
    print("completed")
  })
}