I am looking on the AFNetworking site that GZIP compression is supported \" Gzip decompression from server responses is already built into AFNetworking, as NSURLConnection will
AFAIK NSURLConnection uses gzip decompresson by default and AFNetworking builds on the top of NSURLConnection. So, you shouldn't have to enable it.
NSURLConnection
It seems you need to add a HTTP header :
[self setDefaultHeader:@"Accept-Encoding" value:@"gzip"]
To the AfNetworking HTTP client.