When the user opens the application, he sees and hears the message: “do not forget to activate your gps”.
Then the text disappears from the screen to make room.
You can use location sensor to check whether service is enable or not. If not you can set to enable automatically… (location sensor will present in default block section)
Sorry, because of the translator, I did not understand your answer correctly.
I checked “activated” the position sensor. But I can’t turn on the user’s gps if he doesn’t turn it on himself.