How to add an action to a UIBarButton programmatically? - ios

Question

I've been creating a small iOS app using Swift just for fun, and I have already decided that I want a notification box (a bell-shaped button you can click on to check if there's any notification), and I also wanted to add the bell-shaped button to every screen.
So, I decided to make a base view controller and have other view controllers inherit it. However, that's when my problem arose; I have no idea how to add an action func for that button. Since I create the bell-shaped button programmatically, I cannot just ^ drag and create a new IBaction.
I found this post: link, but this is for a UIButton, not for a UIBarButton, and it didn't work for me.
Sorry for this long question. Below is a simple, one-sentenced question:
MY PROBLEM
How can I add an action to a UIBarButton programmatically?
UPDATE
Here's my base view controller:
import UIKit
class BaseViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// add a notification button
let notificationButton = UIBarButtonItem(image: UIImage(systemName: "bell.fill"))
notificationButton.tintColor = .black
self.navigationItem.rightBarButtonItem = notificationButton
}
}
UPDATE2
Here's my new code:
import UIKit
class BaseViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// add a notification button
let notificationButton = UIBarButtonItem(
image: UIImage(systemName: "bell.fill"),
style: .plain,
target: self,
action: #selector(notificationButtonPressed)
)
notificationButton.tintColor = .black
self.navigationItem.rightBarButtonItem = notificationButton
}
#objc func notificationButtonPressed() {
print("Hello")
}
}

Answer 1

You can pass a target-action pair to the initialiser of UIBarButtonItem:
let barButton = UIBarButtonItem(
image: UIImage(systemName: "bell.fill"),
style: .plain,
target: self, action: #selector(buttonTapped)
)
// somewhere in your view controller:
#objc func buttonTapped() {
// do something when the bar button is tapped
}
See the documentation here.
This is similar to UIButton's addTarget(_:action:for:_) method, if you are familiar with that.