Swift: Can't add custom button to navigation controller - ios

Question

I'm trying to create a custom navigation bar, and I'm having difficulty modifying different parts of the navigation bar. I can change the color of the background, but I can't seem to add buttons or change the title.
class CustomNavigationController: UINavigationController {
override func viewDidLoad() {
super.viewDidLoad()
// changing the background color works
self.navigationBar.barTintColor = UIColor.purpleColor()
// none of this works
let leftButton = UIBarButtonItem(title: "Info", style: UIBarButtonItemStyle.Plain, target: self, action: #selector(openInfo))
self.navigationItem.leftBarButtonItem = leftButton
self.navigationItem.title = "MYTITLE"
}
}
I'm not sure if the fact that I'm trying to integrate this NavigationController with a TabBarController is affecting the way the view loads, but this custom NavigationController is being subclassed by each tab in the TabBarController.

Answer 1

According to UINavigationItem class reference, each view controller has its own UINavigationItem instance. "The managing UINavigationController object uses the navigation items of the topmost two view controllers to populate the navigation bar with content", which means its UIViewController's responsibility to create the navigation item content such as left bar item or title.
I can understand that you want to provide the same appearance of navigation bar throughout the app. But why do you want to set the same title for all view controllers? However, if same title and same left bar item for all view controllers is what you need. Here are two solutions:
1). Make an extension to UIViewController:
extension UIViewController {
func customAppearance() {
let leftButton = UIBarButtonItem(title: "Info", style: UIBarButtonItemStyle.Plain, target: self, action: #selector(openInfo))
self.navigationItem.leftBarButtonItem = leftButton
self.navigationItem.title = "MYTITLE"
}
func openInfo() {
// do what you want
}
}
And then whenever you need a customised navigation bar for a view controller, you call this customAppearance function:
let vc = YourViewController()
vc.customAppearance()
2). Subclass the UIViewController:
class CustomViewController: UIViewController {
override func viewDidLoad() {
let leftButton = UIBarButtonItem(title: "Info", style: UIBarButtonItemStyle.Plain, target: self, action: #selector(openInfo))
self.navigationItem.leftBarButtonItem = leftButton
self.navigationItem.title = "MYTITLE"
}
func openInfo() {
}
}
And your every other view controllers subclass this CustomViewController.
For customzing UINavigationBar's appearance, you can set it like:
UINavigationBar.appearance().barTintColor = UIColor.purpleColor()