翻转动画

    CGContextRef context      = UIGraphicsGetCurrentContext();
    [UIView beginAnimations:nil context:context];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.navigationController.view  cache:NO];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationDuration:1.0f];
    [UIView commitAnimations];