[ios] How to set the action for a UIBarButtonItem in Swift

How can the action for a custom UIBarButtonItem in Swift be set?

The following code successfully places the button in the navigation bar:

var b = UIBarButtonItem(title: "Continue", style: .Plain, target: self, action:nil)
self.navigationItem.rightBarButtonItem = b

Now, I would like to call func sayHello() { println("Hello") } when the button is touched. My efforts so far:

var b = UIBarButtonItem(title: "Continue", style: .Plain, target: self, action:sayHello:)
// also with `sayHello` `sayHello()`, and `sayHello():`

and..

var b = UIBarButtonItem(title: "Continue", style: .Plain, target: self, action:@selector(sayHello:))
// also with `sayHello` `sayHello()`, and `sayHello():`

and..

var b = UIBarButtonItem(title: "Continue", style: .Plain, target: self, action:@selector(self.sayHello:))
// also with `self.sayHello` `self.sayHello()`, and `self.sayHello():`

Note that sayHello() appears in the intellisense, but does not work.

Thanks for your help.

EDIT: For posterity, the following works:

var b = UIBarButtonItem(title: "Continue", style: .Plain, target: self, action:"sayHello")

Swift 4/5 example

button.target = self
button.action = #selector(buttonClicked(sender:))

@objc func buttonClicked(sender: UIBarButtonItem) {
        
}

Swift 5

if you have created UIBarButtonItem in Interface Builder and you connected outlet to item and want to bind selector programmatically.

Don't forget to set target and selector.

addAppointmentButton.action = #selector(moveToAddAppointment)
addAppointmentButton.target = self

@objc private func moveToAddAppointment() {
     self.presenter.goToCreateNewAppointment()
}

Swift 5 & iOS 13+ Programmatic Example

1. You must mark your function with @objc, see below example!
2. No parenthesis following after the function name! Just use #selector(name).
3. private or public doesn't matter; you can use private.

Code Example

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    
    let menuButtonImage = UIImage(systemName: "flame")
    let menuButton = UIBarButtonItem(image: menuButtonImage, style: .plain, target: self, action: #selector(didTapMenuButton))
    navigationItem.rightBarButtonItem = menuButton
}

@objc public func didTapMenuButton() {
    print("Hello World")
}

May this one help a little more

Let suppose if you want to make the bar button in a separate file(for modular approach) and want to give selector back to your viewcontroller, you can do like this :-

your Utility File

class GeneralUtility {

    class func customeNavigationBar(viewController: UIViewController,title:String){
        let add = UIBarButtonItem(title: "Play", style: .plain, target: viewController, action: #selector(SuperViewController.buttonClicked(sender:)));  
      viewController.navigationController?.navigationBar.topItem?.rightBarButtonItems = [add];
    }
}

Then make a SuperviewController class and define the same function on it.

class SuperViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
            // Do any additional setup after loading the view.
    }
    @objc func buttonClicked(sender: UIBarButtonItem) {

    }
}

and In our base viewController(which inherit your SuperviewController class) override the same function

import UIKit

class HomeViewController: SuperViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func viewWillAppear(_ animated: Bool) {
        GeneralUtility.customeNavigationBar(viewController: self,title:"Event");
    }

    @objc override func buttonClicked(sender: UIBarButtonItem) {
      print("button clicked")    
    } 
}

Now just inherit the SuperViewController in whichever class you want this barbutton.

Thanks for the read