I just want to know that how can I use url in GDataXML parser for extracting xml data. I have never used it before so please anybody help me.
You asked a non-descriptive question, so there's not much I can do to explain what you need help with.
NSData *data = [[NSMutableData alloc] initWithContentsOfURL:someURL];
NSError *error;
GDataXMLDocument *doc = [[GDataXMLDocument alloc] initWithData:data
options:0 error:&error];
NSLog(@"%@", doc.rootElement);
Take a look at the (numerous) tutorials on the 'net, such as this one.