iOS daemons. are they legal for AppStore?

Can't find out if开发者_如何学Go daemon application can be run on non-jailbroken iPhone. And what is Apple policy about this stuff? I don't really know if my idea is possible at all... I wonder if it's possible to create such a daemon that can intercept outcoming user call and play custom tone signal while remote user does not answer our call. Almost all cell-operators provides a service of custom call tones which means you can listen to some music while waiting for response... This drives me wild.

Plain and simple: It's not allowed.

Taken from the official App Store Review Guidelines

2.8 Apps that install or launch other executable code will be rejected

Apple allows only a limited set of background tasks. They are:

• Background audio
• Voice over IP
• Background location
• Push notifications
• Local notifications
• Task finishing

More details can be found in the iOS developer site. Note, also, that they won't work on an iPhone 3G.

Per your update:

I wonder if it's possible to create such a daemon that can intercept outcoming user call and play custom tone signal while remote user does not answer our call.

No, it's not. Apps cannot interact with calls in any way. Incoming and outgoing calls suspend execution of all other apps.

No; Apple doesn't allow daemon processes. Since iOS 4, it allows apps to go into the background when you push the home button, but that's really just a form off application switching. The app can't do very much while in the background.