How to run my app offline iphone sdk

I'm creating an iphone web app, in this one I'm getting some string values from a web service, and its loaded into an array. And I have created another array with some sample values (strings). My app should run offline, I mean it should work in background, that is the values i'm getting from web service may vary. So if the values from the web service is e开发者_JAVA百科qual to the content in the second array, I need to get an alert. I mean a notification. Note that, it should happen even if the app is not open in the phone.

Thank you.