如何在iOS7上将Navigationbar背景图像添加到MFMailComposeViewController

Question

I am using MFMailComposeViewController.I can't add navigationBar background image to MFMailComposeViewController on ios7.My Code working ios7 before .But doesn't work on ios7.How can I add navigationbar background image to MFMailComposeViewController on ios7?

    MFMailComposeViewController *mailCompose = [[MFMailComposeViewController alloc] init];
    mailCompose.mailComposeDelegate = self;
    [mailCompose setSubject:@"SubjectName"];
    [mailCompose setMessageBody:shareBodyString isHTML:NO];
    if ([self respondsToSelector:@selector(presentViewController:animated:completion:)])
    {
      [self presentViewController:mailCompose animated:YES completion:nil];
    } 
    else {
         [self presentModalViewController:mailCompose animated:YES];
    }

    [mailCompose.topViewController.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"navigationbar-background.png"] forBarMetrics:UIBarMetricsDefault];  // working before ios7 

Answer 1

Use the Appearance Proxy. Following code will target the whole application :

UINavigationBar *navBar = [UINavigationBar appearance];
[navBar setBackgroundImage:[UIImage imageNamed:@"navigationbar-background.png"] forBarMetrics:UIBarMetricsDefault];

If you prefer to target only in MFMailComposeViewController change the first line with this :

navBar = [UINavigationBar appearanceWhenContainedIn:[MFMailComposeViewController class], nil];

Answer 2

If you already customised navigation bar and also want it to apply MFMailComposeViewController, It only allows to do it with UIAppearance proxy. For iOS 7.1.1, i replaced navigation bar background but couldn't change status bar background. Also it greyed out bar button items on subsequent calls. Therefore I stop customising and tried to turn back to default navigation bar style before creating MFMailComposeViewController

[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleDefault];
[[UINavigationBar appearance] setBarStyle:UIBarStyleDefault];
[[UINavigationBar appearance] setTintColor:nil];
[[UINavigationBar appearance] setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIColor blackColor],NSForegroundColorAttributeName,[UIFont fontWithName:@"Helvetica-Bold" size:18.0], NSFontAttributeName, nil]];

 MFMailComposeViewController *mailComposer =[[MFMailComposeViewController alloc] init];