Get the text on placing a sign

Hey, i want to know how to get the Text on the sign when he is placed.
I have tried By getting the id and checking tiles but don't work and i tried by using
Signchangeevent but that dont work correctly.
What i want:
When a player place a sign to get the text and to check if he is op, if he isn't op break the sign.
I just want to know the event not the plugin i don't see how to do it

 

okay thanks..
but i want a event

an event like BlockPlaceEvent but i want to get the tile of the sign and get the text

 

PHP:

public function onBreak(\pocketmine\event\block\BlockBreakEvent $e){
       $b = $e->getBlock();
       $p = $e->getPlayer();
       $tile = $b->getLevel()->getTile($b);
       if($tile instanceof \pocketmine\tile\Chest){
              $text = $tile->getText();
               if(!$p->isOp()){
                   $b->getLevel()->setBlockIdAt($b, 0);
               }
       }
}

 

okay so i didnt mean exactly what i want no problem
i retry to explain what i want.
I want to get The text of a sign when a player place that sign
i tried

PHP:

public function Changesign(SignChangeEvent $event){
    $player= $event->getPlayer();
    if($event->getLine(0)=="[KITADMIN]"){
        $text= $event->getLines();
    if(!$player->isOp()){
        return $event->setCancelled(true);
//here i want to cancel the event or just set the block like kyd said
    }

 

With code that I proved you can get it.. $text variable is string with the text and now you can only compare it with string

 

That work on the EventOnPlace?
Because i want to get the text when the sign is placed

 

If you are setting the text in same time when sign is placed, then it will work.. But if you are editing the sign after you place then use SignChangeEvent

 

SignChangeEvent does not return anything.
Change to

PHP:

$event->setCancelled(true);
return;