Adding shadow to a UINavigationControllerer - iphone

Question

I'm trying to add shadow to a UINavigationController. My have is based on NavController and i'm trying to add a shadow like in game centers. I have this so far. It works n a UINavigationnBar but i'm trying to get it to work throughout the entire app.
CGColorRef darkColor = [[UIColor blackColor] colorWithAlphaComponent:.5f].CGColor;
CGColorRef lightColor = [UIColor clearColor].CGColor;
CAGradientLayer *newShadow = [[[CAGradientLayer alloc] init] autorelease];
newShadow.frame = CGRectMake(0, 44, 320, 10);
newShadow.colors = [NSArray arrayWithObjects:(id)darkColor, (id)lightColor, nil];
CALayer *superlayer = self.newShadow.superlayer;
[self.newShadow removeFromSuperlayer];
[superlayer addSublayer:self.newShadow];
[self.navigationBar.layer addSublayer:superlayer];
It works directly on a UINavigationBar but applying to a NavigationController project it fails. It builds but won't add the shadow. Any ideas?
EDIT:
I have been trying different approaches to this. I successfully created the gradient by using a shape.
#implementation UINavigationBar (UINavigationBarCategory)
- (void)drawRect:(CGRect)rect {
UIImage *backgroundImage;
backgroundImage = [UIImage imageNamed:#"nav.png"];
[backgroundImage drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
CGContextRef context = UIGraphicsGetCurrentContext();
CGColorSpaceRef myColorspace = CGColorSpaceCreateDeviceRGB();
size_t num_locations = 2;
CGFloat locations[2] = { 1.0, 0.0 };
CGFloat components[8] = { 1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 0.0, 0.5 };
CGGradientRef myGradient = CGGradientCreateWithColorComponents(myColorspace, components, locations, num_locations);
CGPoint myStartPoint, myEndPoint;
myStartPoint.x = 0.0;
myStartPoint.y = 0.0;
myEndPoint.x = 0.0;
myEndPoint.y = 54.0;
CGContextDrawLinearGradient (context, myGradient, myStartPoint, myEndPoint, 1);
}
I can't get the gradient below the UINavigationBar and its overlaying the image. I can't seem to get this to work. What i'm trying to do is add the same shadow Game Center has. I have tried a few different ways. All I need to do here is get this to lie underneath the UINavigationBar allowing the image to be on top and have a little part of the shadow lie on top on the UITableView so when you scroll up its above the UITableView. If you fire up Game Center you'll see exactly what i'm talking about.

Answer 1

I believe you should add it to the
UINavigationController.view.layer
As the UINavigationController he is not a UIView child.
if already you did so, an other way to effect the navigationbar, consistently all over the app is to use the UINavigationBarCategory:
you sould pace this at the end of your delegate - after the #end
#implementation UINavigationBar (UINavigationBarCategory)
- (void)drawRect:(CGRect)rect {
//implement your design
}
#end
EDIT
in this link you can find basic info on how to draw the bar:
An iPhone Graphics Drawing Tutorial using Quartz 2D
and here you can find how to add a shadow:adding shadow with quartz 2d
Good luck

Answer 2

You could subclass UIView and use your existing code to draw the shadow by overriding -drawRect:. Then wherever its needed, create it and add it to the view of the navigation controller.
Consider this example
CGFloat screenWidth = [UIScreen mainScreen].applicationFrame.size.width;
ShadowView *shadowView = [[ShadowView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, screenWidth, 20.0f)];
[self.navigationController.view insertSubview:shadowView atIndex:0];
By adding it to the view of the navigationController at index 0, you're effectively overlaying it on top of whatever the view controller is displaying. You could further improve this by checking for the scale of the main screen to appropriately calculate the height of the shadow view so that it will appear correctly on all devices regardless of having a retina display.