Fading out custom navbaritem with iOS 7.0 - ios

Question

I have been working with iOS 7 and in one of my navigation controller and for some reason I had to use custom back button (with back arrow image and text next to it) as leftBarButtonItem. Now, in iOS 7 when an action sheet or alert is shown in the screen, it fades out the left and right bar item buttons. But with my custom button only text fades out and for back arrow button I have to do special handling. Is there a direct way of doing this:
Here is my code:
Adding custom button (PS: I have to go by custom button for some reasons):
- (void)showCustomBackButton {
UIButton *aCustomBackButton = [UIButton buttonWithType:101];
[aCustomBackButton addTarget:self action:#selector(backAction) forControlEvents:UIControlEventTouchUpInside];
[aCustomBackButton setTitle:#"Back" forState:UIControlStateNormal];
UIImage *backArrow = [UIImage imageNamed:#"backArrowImage"];
UIImageView *imageView = [[UIImageView alloc]initWithImage:#"backArrow"];
[imageView setFrame:CGRectMake(kScreenOrigin, topMargin, backArrow.size.width, backArrow.size.height)];
[aCustomBackButton addSubview:imageView];
UIBarButtonItem *aNegativeSpacer = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
aNegativeSpacer.width = -8.0;
UIBarButtonItem *aLeftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:aCustomBackButton];
aLeftBarButtonItem.tag = 100;
self.navigationItem.leftBarButtonItems = #[aNegativeSpacer, aLeftBarButtonItem];
}
- (void)showCustomBackButtonFaded {
UIBarButtonItem *aBarButtonItem = [self.navigationItem.leftBarButtonItems lastObject];
if (aBarButtonItem && aBarButtonItem.tag == 100) {
UIButton *aCustomBackButton = [UIButton buttonWithType:101];
[aCustomBackButton addTarget:self action:#selector(backAction) forControlEvents:UIControlEventTouchUpInside];
[aCustomBackButton setTitle:#"Back" forState:UIControlStateNormal];
UIImage *backArrow = [UIImage imageNamed:#"fadedBackArrow"];
UIImageView *imageView = [[UIImageView alloc]initWithImage:backArrow];
[imageView setFrame:CGRectMake(kScreenOrigin, topMargin, backArrow.size.width, backArrow.size.height)];
[aCustomBackButton addSubview:imageView];
UIBarButtonItem *aNegativeSpacer = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
aNegativeSpacer.width = -8;
UIBarButtonItem *aLeftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:aCustomBackButton];
self.navigationItem.leftBarButtonItems = #[aNegativeSpacer, aLeftBarButtonItem];
}
}