iPhone app getting XML then refreshing it at intervals

Question

I have an app which gets some data from the web via an XML document. I have this working fine and have followed apples SeismicXML example (uses NSURLRequest etc). I am very new to this so I have to admit that I do not totally understand all the code that gets the XML - but it is working. My problem is that my app may be running for some time so I want to be able to refresh the XML every now and again and check to see if it is different. If it is different I need to update my contents. Basically this means my questions are....

1. Is there a standard way of doing this?
2. I was thinking of creating a timer to call the function which parses the XML but I can't figure out which function to call.

If anyone can give me any pointers or even better examples of this it would be fab. Thanks

Answer 1

An NSTimer is the way to kick off a process that needs performing every x seconds

[NSTimer scheduledTimerWithTimeInterval:5 
                                 target:self 
                               selector:@selector(theXMLMethod)
                               userInfo:nil
                                repeats:YES];

This sets a timer of 5 seconds that calls the theXMLMethod method.