Question

My application triggers the iPhone Dialer and goes to background via the App Delegate.
Somewhere in the AppDelegate.m file this is called:

- (void) applicationDidEnterBackground: (UIApplication *) application
{
    [self terminate];
}

When I am finished with my external app (Dialer) the application is launched again but most of the GUI parts are unresponsive.

Does it ring a bell? How could I debug this issue? Let me know if you need more info.

To be more helpful. The application is an address book that each entry is dialable and when click the iOS app is called. During the call I want to be able to open my app to browse information

Answer 1

I am assuming that your main issue here is that you do not consider the effects of being suspended. Please see this question: iOS 4 resume from background

Then consider reading up on an apps state cycle, which you can find here
Among the things of importance found in this article are:

To help reduce your app’s memory footprint, the system automatically purges some data allocated on behalf of your app when your app moves to the background.

1. The system purges the backing store for all Core Animation layers. This effort does not remove your app’s layer objects from memory, nor does it change the current layer properties. It simply prevents the contents of those layers from appearing onscreen, which given that the app is in the background should not happen anyway.
2. It removes any system references to cached images. (If your app does not have a strong reference to the images, they are subsequently removed from memory.)
3. It removes strong references to some other system-managed data caches

In other words, the state of your application might not be the one you had when you were put in the background. The entirety of this process is too large to elaborate here, and should instead be researched through the documentation provided by Apple, which I have linked to above.