RotationHandling.swift

    public override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {
        super.viewWillTransitionToSize(size, withTransitionCoordinator: coordinator)
        // Before rotation (willTransitionToInterfaceOrientation)
        // ... Do stuff that should happen before rotation ... //
        coordinator.animateAlongsideTransition({ (context) in
                // During rotation
                // ... Do stuff that should happen during rotation ... //
            },
            completion: { (context) in
                // After rotation (didTransitionToInterfaceOrientation)
                // ... Do stuff that should happen after rotation ... //
            })
    }