[英]Is it possible to simulate gravity to an object / UIView in UIDynamicKit?
[英]Moving an object (UIView) in Swift with gravity/collision/elasticity already setup
我想快速创建一个从屏幕顶部开始并落到屏幕底部并停留在那里的正方形。 我还希望能够用我的手指将它拖向顶部并使其再次落向屏幕底部。 关于如何做到这一点的任何提示?
我已经能够创建一个落在屏幕底部的正方形。 我也可以用手指移动它。 但问题是,每当我移动它时,方块就停留在同一个地方。 我移动它后,重力/碰撞/弹性似乎不起作用。 我希望我的手指离开方块后它会掉下来。 请参阅下面的我的代码的摘录。 可能有一些简单的东西我想念。 任何提示将不胜感激。
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()
}
}
您应该在平移手势开始时从UIDynamicAnimator
删除该项目,并在它结束时将其添加回来。
当一个视图被添加到动态动画师时,它的位置应该由动画师和动画师单独确定。 从动画师中删除项目将允许视图使用其框架正常定位。 将它添加回动画师将导致动画师从当前状态恢复定位。
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特性),您应该调用animator.updateItem(usingCurrentState: myDynamicItem)
,其中myDynamicItem
是您要更新的项目。
谢谢贝优武夫。 animator?.removeAllBehavior() 在平移手势例程中发挥了作用
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