Calling function from another ViewController in swift

As of swift 4.1 today, this code worked for me:

Put this in sending controller:

NotificationCenter.default.post(name: Notification.Name(rawValue: "disconnectPaxiSockets"), object: nil)

Put this in receiving controller viewDidLoad() or viewWillAppear():

NotificationCenter.default.addObserver(self, selector: #selector(disconnectPaxiSocket(_:)), name: Notification.Name(rawValue: "disconnectPaxiSockets"), object: nil)

and then the following function in your receiving controller class:

@objc func disconnectPaxiSocket(_ notification: Notification) {    ridesTimer.invalidate()    shared.disconnectSockets(socket: self.socket)}

Swift 5:

Put this in the Action

NotificationCenter.default.post(name: Notification.Name("NewFunctionName"), object: nil)

Put this in viewdidload() in a different viewcontroller (where is the function you want to use)

NotificationCenter.default.addObserver(self, selector: #selector(functionName), name: Notification.Name("NewFunctionName"), object: nil)

The function

 @objc func functionName (notification: NSNotification){ //add stuff here}

I hope I was helpful

You are creating a NEW copy of FirstVC and calling stop on something that is not yet initialised.

You should really use a delegate in this case, something like

protocol controlsAudio {   func startAudio()   func stopAudio()}class FirstVC: UIViewController, controlsAudio {    func startAudio() {}    func stopAudio() {}    // later in the code when you present SecondVC    func displaySecondVC() {       let vc = SecondVC()       vc.delegate = self       self.present(vc, animated: true)    }}class SecondVC: UIViewController {    var delegate: controlsAudio?    // to start audio call self.delegate?.startAudio)    // to stop audio call self.delegate?.stopAudio)}

So you are passing first VC to the second VC, so when you call these functions you are doing it on the actual FirstVC that is in use, rather than creating a new one.

You could do this without protocols if you like by replacing the var delegate: controlsAudio? with var firstVC: FirstVC? and assigning that, but I wouldn't recommend it