How to add special character like "'" in JSON

How to add special character like "'" in JSON

Is there any way to send some special character like ', " in JSON string,
If I try to send this character in JSON, then I am not able to get success
response.
Here is the code :
NSMutableDictionary *dicWebServiceData = [[NSMutableDictionary alloc] init];
[dicWebServiceData setValue:@"Today's menu" forKey:@"description"];
NSString *strBulkData = [NSString
stringWithFormat:@"bulk_data=[%@]",[dicWebService JSONRepresentation]];
strBulkData = [strBulkData
stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];
NSData *postData = [strBulkData dataUsingEncoding:NSUTF8StringEncoding
allowLossyConversion:YES];
NSURL *url = [NSURL URLWithString:[NSString
stringWithFormat:@"%@%@",webServiceURL,strWebServiceName]];
NSMutableURLRequest *req = [NSMutableURLRequest requestWithURL:url];
[req setHTTPMethod:@"POST"];
[req setTimeoutInterval:6000];
[req setValue:[NSString stringWithFormat:@"%d", postData.length]
forHTTPHeaderField:@"Content-Length"];
[req setValue:@"application/x-www-form-urlencoded charset=utf-8"
forHTTPHeaderField:@"Content-Type"];
[req setHTTPBody:postData];
Is there any way to pass this character in JSON ? Thanks,