Question

I have a button,with touch inside event. while I write following code to change the root viewController, the warning shows:Two-stage rotation animation is deprecated. This application should use the smoother single-stage animation

- (IBAction)fn_login:(id)sender {
    AppDelegate *delegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
    UIWindow *window = delegate.window;
    rootTabViewController* rootVC = [[[rootTabViewController alloc]init]autorelease];
    window.rootViewController = rootVC;
}

rootTabViewController is a UITabbarController.

if using UINavigationBar with UITabbarViewController, the warning is the same.

UINavigationController *navigationCtrl = [[[UINavigationController alloc] initWithRootViewController:rootVC] autorelease];
window.rootViewController = navigationCtrl;

Answer 1

you are assigning rootViewController two time.
once at the time of allocating

    UINavigationController *navigationCtrl = [[[UINavigationController alloc] initWithRootViewController:rootVC] autorelease];

                                                                                     //^here

and second time

window.rootViewController = navigationCtrl;
      ^^here

no need to allocate two time. just remove last line