How do I make the flip animation on a modal view o

问题:

How do I make my flip animation transparent so the view behind it is shown through?

Here's some of my code:

EditInfoViewController *editController = [[EditInfoViewController alloc] initWithNibName:@"EditInfoViewController" bundle:nil];
editController.delegate = self;

UINavigationController *editNavController = [[UINavigationController alloc] initWithRootViewController:editController];

editNavController.modalPresentationStyle = UIModalPresentationCurrentContext;
editNavController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self.navigationController presentModalViewController:editNavController animated:YES];

A picture is worth 1000 words (this was taken during the flip animation):