import UIKit

class PositionViewController: UIViewController {

    @IBOutlet weak var redSquare: UIView!

    override func viewDidLoad() {

        super.viewDidLoad()

        // Do any additional setup after loading the view.

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

    override func viewDidAppear(animated: Bool) {

        UIView.animateWithDuration(1, animations: {

            self.redSquare.center.x = self.view.bounds.width - self.redSquare.center.x})

    }

为啥和老师的效果不一样呢？