let btn1 = UIButton.buttonWithType(.System) as UIButtonbtn1.backgroundColor = UIColor.redColor()btn1.setTitle("Button1", forState: UIControlState.Normal)btn1.frame = CGRect(x: 10, y: 80, width: 300, height: 30)btn1.tag = 100self.view.addSubview(btn1)        let btn2 = UIButton.buttonWithType(.System) as UIButtonbtn2.backgroundColor = UIColor.blueColor()btn2.setTitle("Button2", forState: UIControlState.Normal)btn2.setTitleColor(UIColor.redColor(), forState: .Normal)// set round cornerbtn2.layer.cornerRadius = 10.0btn2.frame = CGRect(x: 10, y: 120, width: 300, height: 30)btn2.tag = 101self.view.addSubview(btn2)        let btn3 = UIButton.buttonWithType(.System) as UIButtonbtn3.setTitle("Button3", forState: UIControlState.Normal)btn3.layer.cornerRadius = 10.0// set borderbtn3.layer.borderWidth = 1btn3.layer.borderColor = UIColor.blueColor().CGColorbtn3.frame = CGRect(x: 10, y: 160, width: 300, height: 30)btn3.tag = 102self.view.addSubview(btn3)        // set listeners// Selector is a struct it convert a string to C pointerbtn1.addTarget(self, action: Selector("onBtnClick:"), forControlEvents: UIControlEvents.TouchUpInside)btn2.addTarget(self, action: Selector("onBtnClick:"), forControlEvents: UIControlEvents.TouchUpInside)btn3.addTarget(self, action: Selector("onBtnClick:"), forControlEvents: UIControlEvents.TouchUpInside)

func onBtnClick(btn:UIButton){    var msg = ""        switch btn.tag{    case 100:        msg = "you clicked button1"    case 101:        msg = "you clicked button2"    case 102:        msg = "you clicked button3"    default:        println("default")    }        // In IOS8 the UIAlertView is deprecated    // now we use UIAlertController    var alert = UIAlertController(title: "Alert", message: msg, preferredStyle: UIAlertControllerStyle.Alert)    var ok = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler:{        (action) in            println("you clicked ok")        })    alert.addAction(ok)    self.presentViewController(alert, animated: true)}