How to generate JSON programmatically using JSON framework for iPhone

Create an array or dictionary of objects representing the information you want to send via JSON. Having done that, send -JSONRepresentation to the array/dictionary. That method returns a JSON string, and you send it to the server.

For instance:

NSDictionary *o1 = [NSDictionary dictionaryWithObjectsAndKeys:
    @"some value", @"key1",
    @"another value", @"key2",
    nil];

NSDictionary *o2 = [NSDictionary dictionaryWithObjectsAndKeys:
    @"yet another value", @"key1",
    @"some other value", @"key2",
    nil];

NSArray *array = [NSArray arrayWithObjects:o1, o2, nil];

NSString *jsonString = [array JSONRepresentation];

// send jsonString to the server

After executing the code above, jsonString contains:

[
    {
        "key1": "some value",
        "key2": "another value"
    },
    {
        "key1": "yet another value",
        "key2": "some other value"
    }
]