If you want to add a subview with animation, try this simple snippet:
PS: Replace myView with the name of the view you want to replace.
CATransition *applicationLoadViewIn =[CATransition animation];
[applicationLoadViewIn setDuration:duration];
[applicationLoadViewIn setType:kCATransitionReveal];
[applicationLoadViewIn setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn]];
[[myView layer]addAnimation:applicationLoadViewIn forKey:kCATransitionReveal];
De gran ayuda este post. Muchas gracias. Os dejo una actualización para Swift 4.0. Un saludo.
let animation = CATransition()
animation.duration = 0.5
animation.type = kCATransitionReveal
animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)
myView.layer.add(transition, forKey: kCATransitionReveal)