If-Match</code> header when updating a file request.
By providing that header, a change will only be performed on the  file request if the <code>etag</code> on the file request still matches the <code>etag</code> provided in the <code>If-Match</code> header.</p>

                      </div>
                      <div class="declaration">
                        <h4>Declaration</h4>
                        <div class="language">
                          <p class="aside-title">Swift</p>
                    