Add matrix rows to an entry through a plugin

pluginService.php

<?php
namespace Craft;

/**
 *  Plugin service
 */
class PluginService extends BaseApplicationComponent
{

    // Optionally pass in an entry ID
    public function addMatrixBlockToEntry($entryId = null)
    {

        if ($entryId) {

            $entry = craft()->entries->getEntryById($bundleId);
            
            // True if entry actually exists
            if ($entry)
            {
                // An entry exists, so add the Matrix block
                $this->addBlockToMatrix($entry);
            }
            else
            {
                Craft::log('Couldn’t find a valid entry to add the matrix to.', LogLevel::Error);
            }

        }

        else
        {
            // No entry, so create one
            $this->createEntry();
        }

    }

    // Create an entry then create a Matrix block
    public function createEntry()
    {

        $entry = new EntryModel();
        $entry->sectionId  = 1;
        $entry->typeId     = 1;
        $entry->enabled    = true;
        $entry->getContent()->setAttributes(array(
            'title' => "Hello World!"
        ));

        $success = craft()->entries->saveEntry($entry);

        if ($success) {
            // Entry was saved successful, add a Matrix block
            $this->addBlockToMatrix($entry);
        }
        else
        {
            Craft::log('Couldn’t save the entry "'.$entry->title.'"', LogLevel::Error);
        }

    }

    // Add a Matrix block to an exisiting entry
    public function addBlockToMatrix($entry)
    {

        $ownerId = $entry->id; // the parent entry

        $block = new MatrixBlockModel();
        $block->fieldId    = 245; // Matrix field's ID
        $block->ownerId    = $ownerId; // ID of entry the block should be added to
        $block->typeId     = 47; // ID of block type
        $block->getContent()->setAttributes(array(
            'text' => "Text for the new block",
        ));

        $success = craft()->matrix->saveBlock($block);

        if (!$success)
        {
            Craft::log('Couldn’t save the entry "'.$entry->title.'"', LogLevel::Error);
        }

    }
}