CATransition for segue animation (pre iOS 7 style) - iphone

Question

I have a custom segue, trying to replicate the push/pop segues of the pre iOS 7 style:
viewControllers animating SIDE-BY-SIDE, with NO darkening. (Is it really that hard!)
The code below works, except:
the exiting page becomes dark on exit
the entering page is dark on entering (gradually becomes normal as it moves into position)
These images illustrate the problem:
and then...
Is there a way to stop this darkening effect? I would be really grateful for some help.
-(void)perform
{
UIViewController *source = self.sourceViewController;
UIWindow *window = source.view.window;
CATransition *transition = [CATransition animation];
[transition setDuration:2.0];
[transition setDelegate:self];
[transition setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]];
[transition setType:#"push"];
[transition setSubtype:kCATransitionFromRight];
[window.layer addAnimation:transition forKey:kCATransition];
[window setRootViewController:self.destinationViewController];
}

Answer 1

These 2 functions work fine for me, although the code is pretty similar to yours, I hope it helps.
+(void) modalRight:(UIViewController*)vc destvc:(UIViewController*)viewCtrl{
CATransition *transition = [CATransition animation];
transition.duration = 0.3;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromRight;
[vc.view.window.layer addAnimation:transition forKey:nil];
[vc presentModalViewController:viewCtrl animated:NO];
}
+(void) modalLeft:(UIViewController*)vc{
CATransition *transition = [CATransition animation];
transition.duration = 0.3;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromLeft;
[vc.view.window.layer addAnimation:transition forKey:nil];
[vc dismissModalViewControllerAnimated:NO];
}