transitionFromView and indexes

I'm working with a controller (MAIN) that manage how presents 2 other controllers (A and B) views in its main view. In MAIN controller View i have a BUTTON created into the MAIN view xib. BUTTON must be over A and B view.

So this's the view hierarchy structure i need :

MAIN.VIEW
      |------A or B view (index 0)
      |------BUTTON      (index 1)

Here how i create A and B into MAIN:

//MAIN CONTROLLER viewDidLoad
- (void)viewDidLoad {
    [super viewDidLoad];

    self.A = [[A alloc] init];
    self.B = [[B alloc] init];

    //Start from A view visible in MAIN
    [self.view insertSubview:self.A.view atIndex:0]; 
}

After a specific action call i want to insert controller B view and remove A. I read about transitionFromView and i tried to use it this way:

[UIView tr开发者_开发百科ansitionFromView:self.A.view
                    toView:self.B.view
                  duration:1.0
                   options:UIViewAnimationOptionTransitionFlipFromRight
                completion:^(BOOL finished) {
                    if (finished) {
                        //nothing for now...
                    }
                }]; 

The problem here is that after flip animation B view is over BUTTON and doesn't take exactly the place of A in my hierarchy (A was at index 0)

I can add this code into completion Block :

[self.view sendSubviewToBack:self.B.view];

But i think it's a little tricky solution :P (and it's not a good solution too, because it seems appear effectively at the end of the animation with a bad graphic effect...)

Which is the best way to be sure that A and B are placed at index 0 ?

May be a bug in the SDK. There is a Bug report at OpenRadar with exactly this behaviour.