Basic example of a Facebook Messenger Bot

facebook-messenger-bot.php

<?php
// parameters
$hubVerifyToken = 'TOKEN123456abcd';
$accessToken = "xxx";

// check token at setup
if ($_REQUEST['hub_verify_token'] === $hubVerifyToken) {
  echo $_REQUEST['hub_challenge'];
  exit;
}

// handle bot's anwser
$input = json_decode(file_get_contents('php://input'), true);

$senderId = $input['entry'][0]['messaging'][0]['sender']['id'];
$messageText = $input['entry'][0]['messaging'][0]['message']['text'];

if(!empty($messageText))
{
	$answer = "I don't understand. Ask me 'hi'.";
	if($messageText == "hi") {
	    $answer = "Hello";
	}

	$response = [
	    'recipient' => [ 'id' => $senderId ],
	    'message' => [ 'text' => $answer ]
	];
	$ch = curl_init('https://graph.facebook.com/v2.6/me/messages?access_token='.$accessToken);
	curl_setopt($ch, CURLOPT_POST, 1);
	curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($response));
	curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/json']);
	curl_exec($ch);
	curl_close($ch);
}

This is working fine , but How to Add New lines to message Text , Suppose I need to Send this Message :
Hello ,
How are you ...

This is being sent as Hello , How are you ... All text in displayed same line in Messenger Chat ...