The user will be prompted enter his address in a textfield and in the backend I want to get the location coordinates of the address.
I’m using geocoding service from google but not any of their APIs. I read somewhere in their document that “use of the geocoder for any purpose other than obtaining locations that will be displayed using the google maps APIs is a violation of the Terms of Service”.
And this is how HTTP request I use
http://maps.googleapis.com/maps/api/geocode/json?address=ADDRESS_STRING&sensor=false
Can I do this? I’m confused because I'm not showing any map at all but I want to get the coordinates. Will this be violating their terms?
Unfortunately, yes, I think you'd be breaking Google's rules here. See also this answer.
You could still use iOS' built-in forward-geocoding engine. See here for the docs.