UIViewController transition - objective-c

Question

I have UIViewControllers A and B, they are allocated in AppDelegate. I need to apply transition to them. How to transit them without reallocating a

Answer 1

try

UIViewController* controller1;
UIViewController* controller2;
[controller1 transitionFromViewController:controller1 toViewController:controller2 duration:0.5f options:0 animations:nil completion:nil];

or

if on top of navigationtroller - controller1 then

UINavigationController* nav;
[nav pushViewController:controller2 animated:YES];