Do a simple json POST using RESTKit

For older RestKit

You probably have something like this in your delegate:

    objectManager.serializationMIMEType = RKMIMETypeFormURLEncoded;

You want it to be:

    objectManager.serializationMIMEType = RKMIMETypeJSON;

For RestKit v.20:

    // thanks  ColdLogic (from his comment)    [objectManager setRequestSerializationMIMEType:RKMIMETypeJSON];

I had the same problem, and this is what solved it for me. Note, in my scenario, I only wanted to access RKRequest.

NSDictionarty *dictNSError *error; NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dict options:0 error:&error];if (!jsonData) {    NSAssert(FALSE, @"Unable to serialize JSON from NSDict to NSData"); } else {    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];    request.params = [RKRequestSerialization serializationWithData:[jsonString dataUsingEncoding:NSUTF8StringEncoding] MIMEType:RKMIMETypeJSON];}

The key for me was the 'MIMEType:RKMIMETypeJSON' in the last line. Since I only wanted to use RKRequest, this was how I needed to set the MIME type. Otherwise, I would use Paul Cezanne's suggestion.