iOS sorting array of dictionaries by key

Json: (

        {

        "eef_name" = "Viswa Bell";

        "eua_address" = "Chennai, Tamil Nadu, India";

        "eua_id" = 8;

        "eua_mobile_no" = 9600089555;

    },

        {

        "eef_name" = "Hiramani Barman";

        "eua_address" = "Alwarpet, Chennai, tamilnadu, india";

        "eua_id" = 117;

        "eua_mobile_no" = 9840504444;

    },

        {

        "eef_name" = "Arvind Kumar";

        "eua_address" = "Chennai, Tamilnadu - 18, India";

        "eua_id" = 1;

        "eua_mobile_no" = 9952800777;

    },

        {

        "eef_name" = "Bindu ";

        "eua_address" = Chennai;

        "eua_id" = 71;

        "eua_mobile_no" = 8678902999;

    }

)

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"eef_name" ascending:YES];

            NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];

            NSArray *sortedArray = [mymutablearray sortedArrayUsingDescriptors:sortDescriptors];

           mymutablearray = [NSMutableArray arrayWithArray:sortedArray];