UIImagePickerController rotation, landscape only, Xcode 7, iOS 9

I am coding iPad app with only landscape used. I use UIImagePickerController to access photo library.

I used the following code in AppDelegate.m to rotate photo library view to landscape.

- (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
{
    return UIInterfaceOrientationMaskAll;
}

This worked with Xcode 6 and iOS 8, but does not work with Xcode 7 and iOS 9. Photo library view is fixed to portrate.

I know - (NSUInteger) changed to - (UIInterfaceOrientationMask) , and I tried it but still does not work.

The similar question has already been posted…

https://forums.developer.apple.com/message/64999#64999

…but, it seems no answer so far.

I have no idea how to solve this problem.

Could anyone help me?