“无法识别的选择器发送到实例”在swift

class ViewController: UIViewController,UITextViewDelegate {

    var textView: UITextView!

    init(nibName nibNameOrNil: String?,bundle nibBundleOrNil: NSBundle?) {
        super.init(nibName: nibNameOrNil,bundle: nibBundleOrNil)
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        var widthField = self.view.bounds.size.width - 10
        var heightField = self.view.bounds.size.height - 69 - 221
        var textFieldString: String! = ""
        //Set up text field
        self.textView = UITextView(frame: CGRectMake(5,64,widthField,heightField))
        self.textView.backgroundColor = UIColor.redColor()
        self.view.addSubview(self.textView)
        //Set up the New button
        var newButtonString: String! = "New Note"
        var heightButton = 568 - heightField - 1000
        let newButton = UIButton(frame: CGRect(x: 5,y: 5,width: widthField,height: 50)) as UIButton
        UIButton.buttonWithType(UIButtonType.System)
        newButton.setTitle(newButtonString,forState: UIControlState.Normal)
        newButton.backgroundColor = UIColor.redColor()
        newButton.addTarget(self,action: "buttonAction:",forControlEvents: UIControlEvents.TouchUpInside)
        self.view.addSubview(newButton)

    }

    func buttonAction() {
        println("tapped button")
    }
}

当我按下iOS模拟器中的按钮时，我收到错误“无法识别的选择器发送到实例”。该应用程序打开正常，但按下按钮，它只是崩溃。