iOS 7 相机隐藏状态栏，dismiss时消除下坠20像素动画

gistfile1.m

@interface CustomImagePickerController : UIImagePickerController
{
    BOOL m_bWillDisappear;
}
@end

@implementation CustomImagePickerController

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    m_bWillDisappear = NO;
}

- (void)viewWillDisappear:(BOOL)animated {
    m_bWillDisappear = YES;
    [super viewWillDisappear:animated];
    
    if ([self respondsToSelector:@selector(setNeedsStatusBarAppearanceUpdate)]) {
        [self setNeedsStatusBarAppearanceUpdate];
    }
}

#pragma mark - StatusBar

- (UIStatusBarStyle)preferredStatusBarStyle
{
    return UIStatusBarStyleLightContent; // change this to match your style
}

- (BOOL)prefersStatusBarHidden {
    switch (self.sourceType) {
        case UIImagePickerControllerSourceTypeCamera:
            if (m_bWillDisappear) {
                return [self.navigationController.presentingViewController prefersStatusBarHidden];
            }
            else {
                return YES;
            }
            break;
        default:
            return NO;
            break;
    }
}

- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation {
    return UIStatusBarAnimationNone;
}

- (UIViewController *)childViewControllerForStatusBarHidden {
    switch (self.sourceType) {
        case UIImagePickerControllerSourceTypeCamera:
            return nil;
            break;
        default:
            return [super childViewControllerForStatusBarHidden];
            break;
    }
}

@end