具体问题原因是url中输入的有中文，那么这个就看作非法的字符无法识别。这种的必须使用post方式来发送消息。具体为：

            tmp = mainurl;

            [parameters appendString:key];

            [parameters appendString:value];

NSURL * downloadUrl = [NSURL URLWithString:self.strURL];

        NSMutableURLRequest *requestL = [NSMutableURLRequest requestWithURL:downloadUrl

                                                                cachePolicy:NSURLRequestReloadIgnoringCacheData

                                                            timeoutInterval:60.0];

        [requestL setHTTPMethod:@"POST"];

        NSString *postString = parameters;

        [requestL setHTTPBody:[postString dataUsingEncoding:NSUTF8StringEncoding]];

        NSLog(@"the post body is %@",[NSString stringWithFormat:@"%@", postString]);