Do you have to add it programmatically? Or there is an option from the main.storyboard interface builder?and if there is a way from storyboard , How do you add it ?
Something like this :
You would have to add it programatically.
Do this in your UINavigationController Class
self.navigationBar.shadowColor = UIColor.blackColor().CGColor
self.navigationBar.shadowOffset = CGSizeMake(5, 5)
self.navigationBar.shadowRadius = 5