function withCORSHeaders(Response $resp) {
    return $resp
        ->withHeader('Access-Control-Allow-Origin', '*')
        ->withHeader('Access-Control-Allow-Headers', 'X-Requested-With, Content-Type, Accept, Origin, Authorization');
}

$app->options('/guides', function (Request $req, Response $resp, array $args) use ($container) {
        return withCORSHeaders($resp)
            ->withHeader('Access-Control-Allow-Methods', implode(',', ['GET', 'POST']));
    });

$app->get('/guides', function (Request $req, Response $resp, array $args) use ($container) {
        $guides = $container->get('db')->table('guides')->get();
        return withCORSHeaders($resp)->withJson($guides);
    });