segmentedcontrol / textfield / DidChange - ios

Question

I have a segmentedControl that give a string to a textfield. also i have 2 another textfields. one is for user input and the second for make a calculation from segmentedcontrol textfield and user input textfield. How can i automatically update the calculation textfield when segmentedcontrolindex will change.
For user input textfield the textfielddidchangemethod works. Thanks
#IBOutlet weak var segmentedcontrol: UISegmentedControl!
#IBOutlet weak var textf: UITextField!
#IBOutlet weak var textf1: UITextField!
#IBOutlet weak var textf2: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
textf.delegate = self
textf1.delegate = self
textf2.delegate = self
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func textf1(sender: AnyObject) {
let result = (textf.text! as NSString).doubleValue * (textf2.text! as NSString).doubleValue
textf1.text = String(format:"%.2f", result)
}
#IBAction func segmentedcontrolAction(sender: AnyObject) {
if(segmentedcontrol.selectedSegmentIndex == 0)
{
textf2.text = "5";
}
else if(segmentedcontrol.selectedSegmentIndex == 1)
{
textf2.text = "10";
}
else if(segmentedcontrol.selectedSegmentIndex == 2)
{
textf2.text = "15";
}
}

Answer 1

#IBAction func segmentedcontrolAction(sender: AnyObject)
{
if(segmentedcontrol.selectedSegmentIndex == 0)
{
textf2.text = "5";
}
else if(segmentedcontrol.selectedSegmentIndex == 1)
{
textf2.text = "10";
}
else if(segmentedcontrol.selectedSegmentIndex == 2)
{
textf2.text = "15";
}
let result = (textf.text! as NSString).doubleValue * (textf2.text! as NSString).doubleValue
textf1.text = String(format:"%.2f", result)
}