button

self.navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.done, target: self, action: #selector(self.toAdd))
    
    
    @IBAction func toAdd()  {
        print("123")
    }
    
    @IBAction func doSomething(sender: UIButton){
        
    }
    @IBAction func doSomething2(sender: UIButton, forEvent event: UIEvent){
        
    }