How to interrupt SafeSignal in ReactiveSwift?

Question

Hi I am new to reactive swift. In my new project I am using ReactiveSwift. I am observing value by using SafeSignal variable. I want to interrupt the signal before getting the value. Please help me out in this issue.

Answer 1

In general, when you observe on a Signal or start a SignalProducer, you will get a Disposable back.

This can be used to end the observation:

let property = MutableProperty<Int>(0)
let signalDisposable = property.signal.observeValues {
  print("Signal: \($0)")
}

let producerDisposable = property.producer.startWithValues {
  print("Producer: \($0)")
}


property.value = 1            // Signal and Producer receive value 1
signalDisposable?.dispose()   // End signal observation
property.value = 2            // Only producer receives value 2
producerDisposable.dispose()  // End producer observation
property.value = 3            // No one receives value 3

Cancelation of running work

If you're creating your own SignalProducer for some (longer) work, you'll have to keep disposal in mind in order to stop ongoing work:

let performNetworkCall = SignalProducer<Data, Error> { (observer, disposable) in
  let url = URL(string: "https://www.download.com")!
  let downloadTask = URLSession.shared.dataTask(with: url, completionHandler: { (data, _, error) in
    // Handle completion
  })
  downloadTask.resume()
  disposable.observeEnded {
    // Cancel the download on disposal!
    downloadTask.cancel()
  }
}

Otherwise, your observer will be detached, but the work started by the observer will still resume