Magento how to programmatically subscribe

Step 1: Define Function

Magento 1


<?php

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

Magento 2


/**
* @var \Magento\Newsletter\Model\Subscriber
*/
protected $_subscriber;

public function __construct(
    \Magento\Newsletter\Model\Subscriber $subscriber
){
    $this->_subscriber = $subscriber;
}

public function execute()
{
    $this->creatingSubscribe();
}

public function creatingSubscribe()
{
    // ...
}

Step 2: Create Function

Magento 1


public function createSubscribe()
{
    $customer = Mage::getModel('customer/customer')
        ->setWebsiteId(Mage::app()->getStore()->getWebsiteId())->loadByEmail('example@magecheck.com');

    $customer->setConfirmation(true);  

    $customer->save();
}

Magento 2


public function creatingSubscribe()
{
    $email = 'example@magecheck.com';
    
    $subscriber = $this->_subscriber;
    $subscriber->subscribe($email);

    $subscriber->save();
}