Magento how to programmatically create product attribute

Step 1: Define Function

Magento 1


<?php

class MageCheck_Tutorial_IndexController extends Mage_Core_Controller_Front_Action 
{
    public function indexAction() 
    {
        $this-> createProductAttribute();
    }
    public function createProductAttribute()
    {
        // ...
    }
}

Magento 2


<?php

namespace MageCheck\Tutorial\Setup;

use Magento\Eav\Setup\EavSetupFactory;
use Magento\Framework\Setup\ModuleContextInterface;
use Magento\Framework\Setup\ModuleDataSetupInterface;
use Magento\Framework\Setup\InstallDataInterface;

class InstallData implements InstallDataInterface
{
    private $eavSetupFactory;
 
    public function __construct(EavSetupFactory $eavSetupFactory)
    {
        $this->eavSetupFactory = $eavSetupFactory;
    }
 
    public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
    {
        $setup->startSetup();
        
	$this->creatingProductAttribute($setup);
 
        $setup->endSetup();
    }
    public function creatingProductAttribute()
    {
        // ...
    }
}

Step 2: Create Function

Magento 1


public function createProductAttribute()
{
    $installer = new Mage_Eav_Model_Entity_Setup('core_setup');
    $installer->startSetup();
    $installer->addAttribute('catalog_product', 'productattribute_example', array(
        'group' => 'General',
        'label' => 'Attribute Example',
        'input' => 'text',
        'type' => 'varchar',
        'required' => 0,
        'visible_on_front' => 1,
        'filterable' => 0,
        'searchable' => 0,
        'comparable' => 0,
        'user_defined' => 1,
        'is_configurable' => 0,
        'global' => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_GLOBAL,
        'note' => '',
    ));
    $installer->endSetup();
}

Magento 2


public function creatingProductAttribute() 
{ 
    $installer = $this->_installer;
    $attribute = $this->_attribute;
    $attributeRepository = $this->_attributeRepository;
    $indexAdmin = 0;
    $indexEnglish = 12;
    $attributes_meta = array(
        'Finish' => array(
            'type' => 'swatch_visual',
            'visible' => true,
            'options' => array(
                'Option 1',
                'Option 2',
            ),
        ),
    );      
    foreach ($attributes_meta as $attribute_label => $attribute_meta) {
        $attribute_type = empty($attribute_meta['type']) ? 'text' : $attribute_meta['type'];
        $attribute_data = array(
            'entity_type_id' => $installer->getEntityTypeId('catalog_product'),
            'attribute_code' => 'extension_attribute',
            'backend_type' => 'int',
            'frontend_input' => 'swatch_' === substr($attribute_type, 0, strlen('swatch_')) ? 'select' : $attribute_type,
            'frontend_label' => [$attribute_label],
            'is_required' => 0,
            'is_user_defined' => 1,
            'is_unique' => 0,
            'is_global' => 1,
            'is_visible' => 1,
            'is_searchable' => 0,
            'is_filterable' => 0,
            'is_comparable' => 0,
            'is_visible_on_front' => 0,
            'is_visible_in_advanced_search' => 1,
            'is_required_in_admin_store' => 0,
            'is_used_in_grid' => 1,
            'is_visible_in_grid' => 1,
            'is_filterable_in_grid' => 1,
        );
        $attribute->setData($attribute_data); 
        $attribute->save();  
        $installer->addAttributeToGroup('catalog_product', 'Default', 'General', $attribute->getId());
    }
}