UINavigationController 從上倒下的動畫

-(void)transitTo
{
    CATransition *transition = [CATransition animation];
    transition.duration = kAnimationDuration;
    transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; 
    transition.type = kCATransitionPush; 
    transition.subtype = kCATransitionFromTop;
    transitioning = YES;
    transition.delegate = self; 
    [self.navigationController.view.layer addAnimation:transition forKey:nil];
    self.navigationController.navigationBarHidden = NO; 
    [self.navigationController pushViewController:tableViewController animated:NO];
}