I've migrated my project from iOS 7 to iOS 8 keeping iOS 7 support. Since i've redone all the graphics i've thrown away the old storyboard and created a new one using the new universal storyboard and size classes.
Everything works fine for iOS 8 iPhone/iPad and iOS 7 iPhone but on iOS 7 iPad i'll keep getting the following error:
[NSKeyedUnarchiver initForReadingWithData:]: data is empty; did you forget to send -finishEncoding to the NSKeyedArchiver?
the app didn't even reach application:didFinishLaunchingWithOptions
and i know the problem is the storyboard, because if i create an empty one the app start fine.
What am i missing? Do i need an ad hoc storyboard only for ipad to support iOS 7? or there is another way?
EDIT:
during some test, i've found that the method that throw the exception is:
[storybord instantiateInitialViewController];
or
[storyboard instantiateViewControllerWithIdentifier:@"id"];
i've launched the application with an empty storyboard and loaded my storyboard in the app delegate. The storyboard is not nil, but the app crash on that method. Loading a view controller that is not the initial one doesn't change the result.