How do I deserialize a JSON string into an NSDictionary? (For iOS 5+)

NSData *data = [strChangetoJSON dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *jsonResponse = [NSJSONSerialization JSONObjectWithData:data
                                                             options:kNilOptions
                                                               error:&error];

For example you have a NSString with special characters in NSString strChangetoJSON. Then you can convert that string to JSON response using above code.

It looks like you are passing an NSString parameter where you should be passing an NSData parameter:

NSError *jsonError;
NSData *objectData = [@"{\"2\":\"3\"}" dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:objectData
                                      options:NSJSONReadingMutableContainers 
                                        error:&jsonError];