Php 在Slim/Userfrosting中设置响应标头

有一个php文件，正在寻找返回json，但不断得到html字符编码错误。。。导航到路线时没有输出

MarkersController.php getMarkersJSON

$markers = array();
while ($rows = mysqli_fetch_assoc($result)) {
    //Assuming "lat" is column name in tester table. Please change it if required.
    $lat= $rows['lat'];
    //Assuming "lng" is column name in tester table. Please change it if required.
    $lng= $rows['lng'];

    $markers = array('lat' => $lat, 'lng' => $lng);
}

$app = new \Slim\Slim();
$app->response->headers->set('Content-Type', 'application/json');
echo json_encode($markers);

}

index.php中的路由

$app->get('/markers/', function () use ($app) {
    $controller = new UF\MarkersController($app);
    return $controller->getMarkersJSON();

---

由于这是一个编码错误，您是否可以尝试将内容类型设置为application/json；字符集=utf-8或尝试从db获取UTF8字符：可能重复