Offline comparison of two arrays iphone sdk

I have two arrays containing string variables. In one array, it contains the values from a web service, it will be updating in every 5 seconds. So, i need to run this app offline and also compare the array with another array that contains some sam开发者_如何学Gople values. If any matches occur, should generate a PushNotification. Is that possible?? If yes how can I implement that? If no, is there any other way?

Please help... Thanks....

Hey I can just give you an idea.
register your app for background app
in did enter background make a background handler and you will get approximately 10 mins to finish the task, after the time is over the handler will call finishing block and in this block again create the background handler you will get again 10 mins and so on, in this way your application will reamin in background. But be aware of watchdog.

P.S. This is just an idea, i dont know the apple's view on this. Hope you will succeed.