Nested UICollectionViews, AutoLayout and rotation in iOS 8

Question

I started to use AutoLayout for a large project and was positively surprised about it. However, now I have to adjust the project to accommodate for rotation and size classes, an

Answer 1

TheKey's response is correct. However, instead of reloading the data, you may just call

UICollectionView.collectionViewLayout:finalizeCollectionViewUpdates()

Example:

override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {
        self.collectionView.collectionViewLayout.invalidateLayout()
        self.collectionView.collectionViewLayout.finalizeCollectionViewUpdates()
    }