Multiple image selection custom widget

I’ve found a solution by myself!
With two lines of code I’m now able to save all the selected images and then retrive them on the front-end.

I have added an array in the JS code part:

// media library script
(function($){
  $(document).ready(function(){
    $(document).on('click', '.upload_image_button', function(e){
      e.preventDefault();
      var button = $(this);

      var file_frame = wp.media.frames.file_frame = wp.media({
        title: 'Seleziona o carica un immagine',
        library: {
          type: 'image'
        },
        button: {
          text: 'Select'
        },
        multiple: true
      });

      file_frame.on('select', function(){
        var img = file_frame.state().get('selection');
        var urls = []; 
        img.each(function(selection){
        urls.push(selection.attributes.url)
        button.siblings('input').val(urls).change();
        });
      });

      file_frame.open();
    });
  });
}(jQuery));

Then on the php part I’ve implemented an explode() and a foreach() loop to get the saved urls and place them inside the slider img tag:

public function widget( $args, $instance )
  {
    $images = explode( ',', $instance['images'] );
    ob_start();
    ?>
    <div class="swiper-container logo-slider" id="featured-logo-slider">
      <div class="swiper-wrapper" id="featured-logo">
        <?php foreach( $images as $image ): ?>
          <img class="swiper-slide" src="https://wordpress.stackexchange.com/questions/355953/<?php echo $image; ?>" alt="" width="100" id="client-logo"/>
        <?php endforeach; ?>
      </div>
      <div class="swiper-scrollbar"></div>
    </div>
    <?php
    echo ob_get_clean();
  }