Unity WWW gzip

I use www to download the file, the code is as follows。

WWW www = new WWW (url, null, new Dictionary(){
{“Accept-Encoding”,“gzip,deflate”}
});

Server nginx open gzip rules, when I am in the mac and ios platform, I received the www.bytes do not need to uncompress, but in the android platform I need to uncompress www.bytes,I did not find the documentation,Can someone help me?

i have to solve this problem, I do not need to add header in www, www will be in the ios android platform automatically extract。