Check the text on a sign?

Let's say i wanted to send a player a message when they interact with a sign that has the world "Hello" on a specific line. How would i go about doing that?

Here's how:

PHP:

public function onTouch(PlayerInteractEvent $event){
    $tile = $event->getPlayer()->getLevel()->getTile($event->getBlock());
    if($tile instanceof \pocketmine\tile\Sign){
        if($tile->getText()[0] === "Hello"){
            //code here
        }
    }
}