Class created for Smart Reply tutorial: https://medium.com/@ibjects/smart-reply-nlp-firebase-mlkit-for-ios-tutorial-4034f3deb243

QuestionViewController.swift

//
//  QuestionViewController.swift
//  WorseThanSiri
//
//  Created by Chaudhry Talha on 9/16/19.
//  Copyright © 2019 ibjects.com. All rights reserved.
//

import UIKit
import Firebase

class QuestionViewController: UIViewController {
    
    @IBOutlet weak var questionTextField: UITextField!
    @IBOutlet weak var answerLabel: UILabel!
    
    var replies: [String] = []
    
    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }
    
    
    @IBAction func submitButtonPressed(_ sender: Any) {
        
        view.endEditing(true)
        self.answerLabel.text = "..."
        
        guard let text = questionTextField.text, !text.isEmpty else {
            return
        }
        
        //Natural Language accept object of type TextMessage
        let message = TextMessage(text: questionTextField.text!, timestamp: Date().timeIntervalSince1970, userID: "nothing", isLocalUser: false)
        
        let nl = NaturalLanguage.naturalLanguage()
        nl.smartReply().suggestReplies(for: [message]) { (result, error) in
            
            guard error == nil, let result = result else {
                return
            }
            
            if result.status == .notSupportedLanguage {
                //The conversation language is not english OR the result doesn't contain any suggestions
                self.answerLabel.text = "I don't understand."
                
            } else if result.status == .success {
                //Successful
                
                for suggestion in result.suggestions {
                    self.replies.append(suggestion.text)
                }
                
                self.answerLabel.text = self.replies.randomElement()
                
                
            } else {
                self.answerLabel.text = "I don't know the answer to that."
            }
            
        }
    }
}