我看不到以下按钮为何引发错误：2014-08-13 00：29：57.674 view1
[26581：842344]-[view1.ViewController buttonAction：]：无法识别的选择器已发送至实例0x797731c0
2014-08-13 00：29：57.677 view1 [26581：842344] *
由于未捕获的异常’NSInvalidArgumentException’而终止应用程序，原因：’-[view1.ViewController
buttonAction：]：无法识别的选择器已发送至实例0x797731c0’。任何帮助表示赞赏。非常感谢

    import UIKit

        class ViewController: UIViewController {

        override func viewDidLoad() {
        super.viewDidLoad()


        func buttonAction(sender:UIButton)
        {
            println("Button tapped")
        }

        let windowsize = CGRect(x: 0, y: 0, width: 320, height: 480)
        let labelsize = CGRect(x: 0, y: 200, width: 140, height: 60)
        let myButton = UIButton(frame: CGRectMake(0, 0, 100, 100))



        let myView = UIView(frame: windowsize)
        let viewwidth = myView.frame.width
        let spaceleft = (viewwidth - labelsize.width)/2

        myView.backgroundColor = UIColor .blackColor()
        let myLabel = UILabel(frame:labelsize)
        myLabel.frame.origin.x = spaceleft
        myLabel.text = "Hello"
        myLabel.font = UIFont(name: "Chalkduster", size: 22)
        myLabel.textColor = UIColor .whiteColor()
        myLabel.textAlignment = NSTextAlignment.Center


        myLabel.backgroundColor = UIColor .redColor()
        //myView.addSubview(myButton)

        myView.addSubview(myLabel)
        self.view.addSubview(myView)



        let button   = UIButton.buttonWithType(UIButtonType.System) as UIButton
        button.frame = CGRectMake(100, 100, 100, 50)
        button.backgroundColor = UIColor.greenColor()
        button.setTitle("Test Button", forState: UIControlState.Normal)
        button.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)
        myView.addSubview(button)



        // 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.
    }


}