Ios 在已设置重力/碰撞/弹性的Swift中移动对象（UIView）

我想在swift中创建一个正方形，从屏幕顶部开始，然后下降到屏幕底部并保持在那里。我也希望能够用我的手指将它拖向顶部，使它再次朝屏幕底部落下。有什么建议吗

我已经能够创建一个落在屏幕底部的正方形。我也能用手指移动它。但问题是，每当我移动它时，正方形就停留在同一个地方。我移动后，重力/碰撞/弹性似乎不起作用。我想让它在我把手指从正方形上拿开后掉下来。下面是我的代码摘录。我可能错过了一些简单的事情。任何提示都将不胜感激

import UIKit

class ViewController: UIViewController {

  var greenSquare: UIView?
  var redSquare:UIView?
  var animator: UIDynamicAnimator?

  override func viewDidLoad() {
    super.viewDidLoad()
    createFallingObject()

    func createFallingObject() {

     //remove square from superview
     redSquare?.removeFromSuperview()

     //create the shape
     var dimen = CGRect(x: 130,y: 25,width: 90,height: 90)
     redSquare = UIView(frame: dimen)
     redSquare?.backgroundColor = UIColor.red

     //then add to the screen
     self.view.addSubview(redSquare!)

     //Initialize the animator
     animator = UIDynamicAnimator(referenceView: self.view)

     //Add gravity to the squares
     let gravity = UIGravityBehavior(items: [redSquare!])
     let direction = CGVector(dx: 0.0, dy: 0.05)
     gravity.gravityDirection = direction

     //Collision
     let boundaries = UICollisionBehavior(items: [redSquare!])
     boundaries.translatesReferenceBoundsIntoBoundary = true

     //Elasticity
     let bounce = UIDynamicItemBehavior(items: [redSquare!])
     bounce.elasticity = 0.3



     // 1. create a gesture recognizer (tap gesture)
     let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleTap(sender:)))


     //add pan gesture Regcognizer to the red square
     let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
     redSquare?.addGestureRecognizer(panGestureRecognizer)


     animator?.addBehavior(boundaries)
     animator?.addBehavior(bounce)
     animator?.addBehavior(gravity)
    }

    //this method handle pan
    func handlePan(_ gestureRecognizer: UIPanGestureRecognizer) {
     if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {

        let translation = gestureRecognizer.translation(in: self.view)
        // note: 'view' is optional and need to be unwrapped
        gestureRecognizer.view!.center = CGPoint(x: gestureRecognizer.view!.center.x + translation.x, y: gestureRecognizer.view!.center.y + translation.y)
        gestureRecognizer.setTranslation(CGPoint.zero, in: self.view)

        //redSquare?.frame.origin.x = translation.x
        //redSquare?.frame.origin.y = translation.y
     }
   }

   // 3. this method is called when a tap is recognized
   func handleTap(sender: UITapGestureRecognizer) {
    createFallingObject()
   }
}

---

当平移手势开始时，应将项目从

UIDynamicAnimator

中删除，并在结束时将其添加回

将视图添加到动态动画师时，其位置应由动画师和动画师单独确定。从动画师中删除该项目将允许视图使用其帧正常定位。将其添加回动画师将使动画师从其当前状态恢复定位

---

或者，如果您需要手动更新项目的位置（即，不基于动画师的物理），您应该调用

animator.updateItem（使用CurrentState:myDynamicItem）

，其中

myDynamicItem

是您要更新的项目。

谢谢beyowulf。animator？.removeAllBehavior（）在平移手势例程中完成了该操作