Semantic UI: Message Hidden or Visible Problems

<div class="ui hidden message"> You can't see me </div>

<div class="ui visible message"> You can always see me </div>

I want to control my page that the message can show or hidden after a form post to server, how can i do it?

On the server, set a variable in your view based on some conditions. Then in your view, set the "hidden" or "visible" class depending on the value of that variable.