SBJSON parsing NSString to NSDictionary

Question

I'm trying to parse an NSString that contains JSON data into an NSDictionary using SBJson 3.0.4, but when I do it, I get this error:

"WebKit discarded an uncaught exception in the webView:shouldInsertText:replacingDOMRange:givenAction: delegate: -[__NSCFString JSONValue]: unrecognized selector sent to instance 0x6ab7a40"

As far as I know (which isn't very far), the JSON I'm getting is valid, so I don't know why this is happening. My code compiles fine too… Here it is:

NSString *tempURL = [NSString stringWithFormat:@"http://maps.googleapis.com/maps/api/geocode/json?address=%@&sensor=true",userInput.text];
NSURL *url = [NSURL URLWithString:tempURL];
NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url 
                                            cachePolicy:NSURLRequestReturnCacheDataElseLoad
                                        timeoutInterval:30];
// fetch the JSON response
NSData *urlData;
NSURLResponse *response;
NSError *error;

// make the synchronous request
urlData = [NSURLConnection sendSynchronousRequest:urlRequest 
                                returningResponse:&response 
                                            error:&error];

// construct a String around the Data from the response
NSString *data = [[NSString alloc] initWithData:urlData encoding:NSUTF8StringEncoding];
NSDictionary *feed = [data JSONValue];