Sulu\Bundle\MediaBundle\Entity\MediaRepositoryInterface::findMediaById PHP Method

    public function findMediaById($id);

 /**
  * Sets a media with a given id as the avatar of a given contact.
  *
  * @param Contact $contact
  * @param array $avatar with id property
  *
  * @throws EntityNotFoundException
  */
 private function setAvatar(Contact $contact, $avatar)
 {
     $mediaEntity = null;
     if (is_array($avatar) && $this->getProperty($avatar, 'id')) {
         $mediaId = $this->getProperty($avatar, 'id');
         $mediaEntity = $this->mediaRepository->findMediaById($mediaId);
         if (!$mediaEntity) {
             throw new EntityNotFoundException($this->mediaRepository->getClassName(), $mediaId);
         }
     }
     $contact->setAvatar($mediaEntity);
 }