pocketmine\utils\VersionString::compare PHP Method

    public function compare($target, $diff = false)
    {
        if ($target instanceof VersionString === false) {
            $target = new VersionString($target);
        }
        $number = $this->getNumber();
        $tNumber = $target->getNumber();
        if ($diff === true) {
            return $tNumber - $number;
        }
        if ($number > $tNumber) {
            return -1;
            //Target is older
        } elseif ($number < $tNumber) {
            return 1;
            //Target is newer
        } elseif ($target->getBuild() > $this->getBuild()) {
            return 1;
        } elseif ($target->getBuild() < $this->getBuild()) {
            return -1;
        } else {
            return 0;
            //Same version
        }
    }

 protected function checkUpdate()
 {
     if ($this->updateInfo === \null) {
         return;
     }
     $currentVersion = new VersionString($this->server->getPocketMineVersion());
     $newVersion = new VersionString($this->updateInfo["version"]);
     if ($currentVersion->compare($newVersion) > 0 and ($currentVersion->get() !== $newVersion->get() or $currentVersion->getBuild() > 0)) {
         $this->hasUpdate = \true;
     } else {
         $this->hasUpdate = \false;
     }
 }