How to create a relational database in ios, where the data is captured from web api, i.e. the data is in json

this is my json data returned from calling the following api call, (oAuth parameters omitted for clarity): http://ift.tt/1FoQ2fJ(here userid, startdate and enddate is dummy,). my json response is as follows:

body =     {
        activities =         (
                        {
                calories = 0;
                date = "2015-01-01";
                distance = 0;
                elevation = 0;
                intense = 0;
                moderate = 0;
                soft = 0;
                steps = 0;
                timezone = "Australia/Brisbane";
            },.......
                      {
                calories = "0.1";
                date = "2014-12-17";
                distance = "5.34";
                elevation = 0;
                intense = 0;
                moderate = 0;
                soft = 0;
                steps = 6;
                timezone = "Australia/Brisbane";
            }
        );
    };
    status = 0;
} 

These data is received from the above api call. Keeping in mind these data is generated from "withings" sensors. Now I want to create a database and store these data locally in my phone. What and how do i do it? I absolutely have no starting point to work. Please someone guide me or if someone has nice tutorials for it, will be really great.Thank you.