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];