Background Thread in iPhone

is it possible in iPhone to run any main Background thread which go for a method after every 5 s开发者_StackOverflow社区econds and it keeps on doing this until my application is closed.while i can go to other screens and that thread keeps on running.

PLease guide or give me some code snippet for this..

Thanks a bunch

---

try performSelectorInBackground from AppDelegate or fire a timer from appDelegate and invalidate that timer when application is going to resignActive.