Turn off non-Wifi Internet access on iOS I want to use internet only via Wifi, and be asked if I want to use the internet via my SIM (3G or so).

How can I do that? Is there a setting for it?
you can turn off cellular data (or your internet over your SIM) when you go to Settings->Cellular (or Mobile data) and then turn of Cellular data.
Or in Romanian:
Configurari->Conexiune celulara and turn off Date celulare

this way you'll use only your wifi connection (if you're connected to WiFi).