Swift - 使用UI Dynamics给UIKit组件添加移动吸附行为

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import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var imageView: UIImageView!

    var dynamicAnimator = UIDynamicAnimator()

    var snap:UISnapBehavior?

    override func viewDidLoad() {

        super.viewDidLoad()

        dynamicAnimator = UIDynamicAnimator(referenceView: self.view)

    }

    @IBAction func tapped(sender:AnyObject){

        //获取点击位置

        let tap = sender as! UITapGestureRecognizer

        let point = tap.locationInView(self.view)

        //删除之前的吸附,添加一个新的

        if self.snap != nil {

            self.dynamicAnimator.removeBehavior(self.snap!)

        }

        self.snap = UISnapBehavior(item: self.imageView, snapToPoint: point)

        self.dynamicAnimator.addBehavior(self.snap!)

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

    }

}