用php json_encode显示阿拉伯字母

I tried the following:

header( 'Content-Type: application/json; charset=utf-8' );
json_encode($data, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_QUOT | JSON_HEX_AMP | JSON_UNESCAPED_UNICODE | JSON_PRETTY_PRINT)

But the output is always:

موعد مع احمد ÙÙŠ بيروت

instead there should be arabic title