ios - Can't receive notification with Firebase in foreground? -

i'm using firebase make notifications server ios.
have 1 problem :
when application in background, no problem, receive notification.
when application in foreground, code print me notification data don't show on gui :/

that's function :

// receive displayed notifications ios 10 devices. func usernotificationcenter(_ center: unusernotificationcenter,                             willpresent notification: unnotification,                             withcompletionhandler completionhandler: @escaping (unnotificationpresentationoptions) -> void){     let userinfo = notification.request.content.userinfo     // print message id.     if let messageid = userinfo[gcmmessageidkey]{         print("message id: \(messageid)")     }      // print full message.     print(userinfo)      // change preferred presentation option     completionhandler([]) } 

do know how can force firebase show notification on gui ? tryed make local notification instead, without results ...

thanks "luca rocchi", when application in foreground, notification ui not show @ all.