Swift 3 and iOS UIMessageAlert

AlertFunctions.swift

// Put these in your UIViewController subclass:

func showAlertMsg(_ title: String, message: String, time: Int) {

    guard (self.alertController == nil) else {
        print("Alert already displayed")
        return
    }

    self.baseMessage = message
    self.remainingTime = time

    self.alertController = UIAlertController(title: title, message: self.baseMessage, preferredStyle: .alert)

    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (action) in
        print("Alert was cancelled")
        self.alertController=nil;
        self.alertTimer?.invalidate()
        self.alertTimer=nil
    }

    self.alertController!.addAction(cancelAction)

    self.alertTimer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(self.countDown), userInfo: nil, repeats: true)

    self.present(self.alertController!, animated: true, completion: nil)     
}

func countDown() {

    self.remainingTime -= 1
    if (self.remainingTime < 0) {
        self.alertTimer?.invalidate()
        self.alertTimer = nil
        self.alertController!.dismiss(animated: true, completion: {
            self.alertController = nil
        })
    } else {
        self.alertController!.message = self.alertMessage()
    }

}

func alertMessage() -> String {
    var message=""
    if let baseMessage=self.baseMessage {
        message=baseMessage+" "
    }
    return(message+"\(self.remainingTime)")
}