Remove Custom Nav Bar on Email Sheet - ios

Question

I have this code in my App Delegate:
[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:#"Nav Bar.png"] forBarMetrics:UIBarMetricsDefault];
This works great, but I use the MFMailComposeViewController and I want it to have the default NavigationBar appearance.
How do I do that?
EDIT:
I tried this code:
[[UINavigationBar appearanceWhenContainedIn: [MFMailComposeViewController class], [UIViewController class], nil] setBackgroundImage:[UIImage imageNamed:#"Textured Background.png"] forBarMetrics:UIBarMetricsDefault];
I've also tried having only this code. Nothing changes. Default Nav bar, including with the Mail View Controller.
I think it could be something with the appearanceWhenContainedIn:. Does anyone know what MFMailComposeViewController would be contained in?

Answer 1

I figured it out! Here's the code:
[[UINavigationBar appearance] setBackgroundImage:nil forBarMetrics:UIBarMetricsDefault];
MFMailComposeViewController *emailVC = [[MFMailComposeViewController alloc] init];
//the rest of the implementation goes here...
[self presentViewController:emailVC animated:YES completion:nil];
Then, I set the nav bar appearance back to normal here:
- (void)mailComposeController:(MFMailComposeViewController*)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError*)error
{
[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:#"Nav Bar.png"] forBarMetrics:UIBarMetricsDefault];
[self dismissViewControllerAnimated:YES completion:nil];
}

Answer 2

You can try this:
[UINavigationBar appearanceWhenContainedIn: [MFMailComposeViewController class], nil]
Which means all navigation bars contained in a MFMailComposeViewController class
From the docs: UIAppearance
This will return the appearance proxy so you can modify it like this:
[[UINavigationBar appearanceWhenContainedIn: [MFMailComposeViewController class], nil] setBackgroundImage:myImage];
Hope that helps.