iOS 4.2: Flip image using block animations

I had this piece of code im my app:

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:1];
[UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:imgView cache:YES];
    imgView.image = img2;
[UIView commitAnimations];

But use of this method is discouraged in iOS 4.0 and later, and I should use transitionWithView:duration:options:animations:completion:

I cant get this to work properly. Can anyone help me? Thx!