Is it possible to customize UINavigationBar by protocol? - swift

Question

I want to customize UINavigationBar for some view controllers. For some reasons, I cannot just simply extend UIViewController. So I was trying to do it by a protocol.
What I have tried:
protocol TransparentNavigationBarProtocol {
func makeNavigationBarTransparent()
}
extension TransparentNavigationBarProtocol where Self: UIViewController {
func makeNavigationBarTransparent() {
if let navController = navigationController {
navController.navigationBar.setBackgroundImage(UIImage(), for: .default)
navController.navigationBar.shadowImage = UIImage()
navController.navigationBar.tintColor = UIColor.white
navController.navigationBar.barStyle = .blackTranslucent
navController.navigationBar.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]
navController.navigationBar.backgroundColor = .clear
}
}
}
I added some breakpoints which show the function had been called successfully but the navigationBar didn't change. So I was wondering is it possible to achieve this by protocols?

Answer 1

For Xcode11, you need set a image, not nil
Also, in your viewcontroller's viewWillAppear, you need call makeNavigationBarTransparent()
func makeNavigationBarTransparent() {
if let navController = navigationController {
navController.navigationBar.setBackgroundImage(UIImage(), for: .default)
navController.navigationBar.shadowImage = UIImage()
navController.navigationBar.tintColor = UIColor.init(red: 74/255, green: 74/255, blue: 74/255, alpha: 1)
navController.navigationBar.barStyle = .default
navController.navigationBar.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor(red: 74/255, green: 74/255, blue: 74/255, alpha: 1)]
}
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
makeNavigationBarTransparent()
}