protected function isNotModified($request, $file)
    {
        $modifiedSince = $request->getHeaderLine('If-Modified-Since');
        if (!$modifiedSince) {
            return false;
        }

        return strtotime($modifiedSince) === $file->lastChange();
    }
protected function isNotModified($request, $file)
    {
        $modifiedSince = $request->getHeaderLine('If-Modified-Since');
        if (!$modifiedSince) {
            return false;
        }

        return strtotime($modifiedSince) === $file->lastChange();
    }
protected function isNotModified ( $ request , $ file ) { $ modifiedSince = $ request -> getHeaderLine ( 'If-Modified-Since' ) ; if ( ! $ modifiedSince ) { return false ; } return strtotime ( $ modifiedSince ) === $ file -> lastChange ( ) ; }
Check the not modified header.

@param \Psr\Http\Message\ServerRequestInterface $request The request to check.
@param \Cake\Filesystem\File $file The file object to compare.
@return bool
Check the not modified header .