使用AFNetworking从Django服务器下载文件

I am using AFNetworking to send a HTTP request to a Django server to download a file to iPhone. However, neither do the console print out "Success" or "Error". I also cannot find the file in the specific dir ".../database". For the server side, the log file is correct ([22/Jan/2015 16:45:49] "GET /main/receivefile/ HTTP/1.1" 200 16811) and I can see the request and there is no error. This is my client side code:I am using AFNetworking to send a HTTP request