Generate a JSON string using Objective-C

I know there are a few frameworks to parse JSON, but how can I generate a JSON string in Objective-C? Will it be something I would have t开发者_如何学Goo write myself, or is there something simple already out there?

I personally like json-framework's use of categories on NSObject over having to go through TouchJSON's CJSONDataSerializer interface.

NSDictionary *dict = [NSDictionary dictionaryWithObject:@"b" forKey:@"a"];
NSString *json = [dict JSONRepresentation];

TouchJSON includes a mechanism to take a dictionary and produce JSON from it:

http://github.com/schwa/TouchJSON

The example code from that page:

NSDictionary *dictionary = [NSDictionary dictionaryWithObject:@"b" forKey:@"a"];
NSError *error = NULL;
NSData *jsonData = [[CJSONDataSerializer serializer] serializeObject:dictionary error&error];

The interface for this framework seems pretty straight forward to use for generating JSON.