creating simple action if NSButton is pressed in swift

The problem lies in the way you add your selector

myButton.action = Selector(printSomething())

The syntax for adding selectors is a bit quirky, you give it a string with the name of the function, so in your case you should write:

myButton.action = Selector("printSomething")

Which should reward you with Hello in your console.

And probably because the syntax is causing people problems it was changed in Swift 2.2, so now you write:

myButton.action = #selector(ViewController.printSomething)

instead. This means that the compiler can help you catch these errors early, which is a great step forward I think. You can read more about it in the release notes for Swift 2.2 here

So...here is your entire example:

import Cocoaclass ViewController: NSViewController {    @objc    func printSomething() {        print("Hello")    }    override func viewDidLoad() {        super.viewDidLoad()        // Do any additional setup after loading the view.        let myButtonRect = CGRect(x: 10, y: 10, width: 100, height: 10)        let myButton =  NSButton(frame: myButtonRect)        view.addSubview(myButton)        myButton.target = self        myButton.action = #selector(ViewController.printSomething)    }    override var representedObject: AnyObject? {        didSet {        // Update the view, if already loaded.        }    }}

Hope that helps you.