NSJSONSerialization - this class kicks @$$!

jsonmagic.m

  NSError *error;
  // turn the responseData into an NSDictionary object
  NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
  NSArray *latestLoans = json[@"loans"];
  NSDictionary *loan = latestLoans[0];

  // build an info object out of the dictionary 
// this is a new way to write dictionaries as of iOS6
NSDictionary *info = @{
                  @"who":loan[@"name"];
                  @"where":loan[@"location"][@"country"];
                  @"what" : [NSNumber numberWithFloat:outstandingAmount]
                    };
  // convert the object o NSData... json!
  NSData *jsonData = [NSJSONSerialization dataWithJSONObject:info
              options:kNilOptions error:&error];