For quite some time I ranted about not being able to use compressed network communcation out-of-the-box on the iPhone.
Despite being undocumented (or I just overlooked the hint), NSURLConnection does gzip decompression transparently!
That’s how to use it:
ensure the webserver sends gzipped content, use e.g. wget to verify:
It should (in case of a gzipped xml document) look like$ wget –header=‘Accept-Encoding: gzip’
–server-response http://example.com/demo.xmlzHTTP/1.1 200 OK … Content-Type: text/xml Content-Encoding: gzip …
If your webserver doesn’t support transparent compression, you can still upload gzipped content and tell the server to send the correct response headers by setting up a .htaccess file:
... AddType text/xml .xml .xmlz AddEncoding gzip .gz .xmlz # inspired by # http://betterexplained.com/articles/ # how-to-optimize-your-site-with-gzip-compression/ # compress all text & html: AddOutputFilterByType DEFLATE text/html text/plain text/xml ...
to verify from within your app, log the response header in the NSURLConnection callbacks:
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse )response { NSLog(@“didReceiveResponse %@: %@“, [response URL], [(NSHTTPURLResponse)response allHeaderFields]); buffer = [[NSMutableData dataWithCapacity:1024*1024] retain]; }
(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)dat { [buffer appendData:dat]; }
(void)connectionDidFinishLoading:(NSURLConnection *)connection { NSLog(@“connectionDidFinishLoading %d bytes”, [buffer length]); [buffer release]; }
It should look like
2009-06-28 14:31:09.722 DemoApp[3981:20b] \
didReceiveResponse http://example.com/demo.xmlz: {
...
"Content-Type" = "text/xml";
"Content-Encoding" = gzip;
"Content-Length" = 123042;
}
...
2009-06-28 14:31:11.619 DemoApp[3981:20b] \
connectionDidFinishLoading 602979 bytes
As you can see we received way more bytes than went over the wire.
- enjoy lightning fast network communication!
P.S.: It seems not to be necessary setting the request header yourself:
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
timeoutInterval:60.0];
// set explicitly:
[request setValue:@"gzip" forHTTPHeaderField:@"Accept-Encoding"];