Get dynamically dictionary key in NSString

I have json dictionary like this:

{
    36946 =     {
        answer = "-2147483648";
        sectionid = 1;
        time = 2;
    };
    36947 =     {
        answer = 3;
        sectionid = 1;
        time = 2;
    };
};

I have to get dynamically key(36946) in NSString so that I can match this string with another string. How Can I get this.

Thanks in advance.