You can see how to create a URL Request with post variables over at this post:
Append data to a POST NSURLRequest
You can find the URL and variable names by inspecting your current form's HTML. In your case post to the URL:
https://docs.google.com/forms/d/1vlYPlNi4xJv6JCHpLrHD6oSrYgUqWOrzF8z6KJjTVuE/formResponse
Paramaters will be entry.1615511943
, entry.1186557728
, etc. You'll also find these in the HTML input's 'name'.
Set the doc type like this:
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"content-type"];
The data itself is just strings, you'll have to build a UI and pull them from there.