Ios7 全屏UIViewController的StatusBarStyle

我目前有一个将状态栏样式设置为“轻内容”的应用程序

[UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleLightContent;

除全屏模式窗口外，此功能正常工作。以下是创建模态UIViewController的代码：

@implementation PostCard
- (id)initWithToRecipients:(NSArray *)toRecipients subject:(NSString *)subject message:(NSString *)message isHTML:(BOOL)isHTML
{
    if ([MFMailComposeViewController canSendMail] && (self = [super init]))
    {
        self.viewController = [MFMailComposeViewController new];
        self.viewController.mailComposeDelegate = self;

        [_viewController setToRecipients:toRecipients];
        [_viewController setSubject:subject];
        [_viewController setMessageBody:message isHTML:isHTML];

        self.viewController.modalPresentationStyle = UIModalPresentationFullScreen;
        self.viewController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    } else {
        NSLog(@"Cannont send mail from current device.");
    }

    return self;
}
...
@end

然后，明信片的视图控制器显示为

[myOtherViewController presentViewController:myPostCard.viewController animated:YES completion:nil];

在全屏模式下，statusBarStyle恢复为黑色内容。如果将modalPresentationStyle更改为UIModalPresentationFormSheet，则灯光内容将保留

有没有办法通过编程设置模式窗口的“statusBarStyle”？或者告诉它从当前UIViewController继承？还是这是一只虫子？注意，我也尝试过设置项目属性，但没有成功

提前谢谢

- (UIStatusBarStyle)preferredStatusBarStyle
{
    return UIStatusBarStyleLightContent;
}