Keep checkboxes from loop checked after refresh

I can't keep the right checkboxes checked after refresh. I have looked at other questions, but nobody seems to deal with this issue where the checkboxes are generated from a for loop (at least I can't find anything on it).

When I check some checkboxes, 3 random ones, I have 3 checked checkboxes when refreshing. However these are always the first 3, instead of the exact ones I checked.

Obviously there is some issue with my code that I should resolve, but it makes me ask another question too. Is it bad practice to generate elements through a loop? I would think it's better as it avoids lines that are more or less duplicates

              $numberOfLanguages = count($languageOptions);
              for ($i = 0; $i < $numberOfLanguages; $i++) {
                $check = '';

                if (empty($_POST['language'][$i])) {
                  $check = '';
                }

                if (!empty($_POST['language'][$i])) {
                  $check = 'checked';
                }

            ?>

                  <li><input type="checkbox" name="language[]" value=" <?php echo $languageOptions[$i] ?>" <?php if($check == 'checked'): ?>checked="checked"<?php endif; ?> /><?php echo $languageOptions[$i] ?></li>

            <?php

              }