Get user selected NSFont using NSFontManager - Unable to override changefont function

I'm trying to allow the user to select a font of his/her choice using the NSFontManager. I could show the font picker using the following code

@IBAction func fontchangeclicked(_ sender: Any) {
            NSFontManager.shared.orderFrontFontPanel(nil)
    
        }

But the NSViewController is unable to recognise this overridden function.

override func changefont(_ sender: Any?) {
        guard let fontManager = sender as? NSFontManager else {
                    return
                }
                let newFont = fontManager.convert(self.globalfont)
                self.globalfont = newFont
       
               }

A list of requirements:

1. It's changeFont instead of changefont.
2. NSObject.changeFont(_:) is deprecated, use NSFontChanging.changeFont(_:) instead.
3. The view controller must adopt NSFontChanging.
4. Your changeFont(_:) is not called when the first responder object handles changeFont(_:).

class ViewController: NSViewController, NSFontChanging {

    func changeFont(_ sender: NSFontManager?) {
        guard let fontManager = sender else {
            return
        }
        let newFont = fontManager.convert(self.globalfont)
        self.globalfont = newFont
    }
               
}