NSString json 车NSDictionary

 NSData *jsonContent = [[userInfo objectForKey:@"acme"] dataUsingEncoding:NSUTF8StringEncoding];

            NSDictionary * jsonDic = nil;

            NSError *error = nil;

            jsonDic =  [NSJSONSerializationJSONObjectWithData:jsonContent options:NSJSONReadingMutableLeaveserror:&error];