Mehmet Tuğrul SARIÇİÇEK,
For your case I can suggest you the following method:
Users can see the connection status on the status bar in the top of the screen.
In case of problems with connection (it can happen even if the connection exist, but not stable) you can catch the problem as Samir Muqimov suggested and display a warning message.
Think, this is better, than hoping that if the connection is set it is 100% works fine.