UICollisionBehavior 忽略屏幕边缘

Question

我有几个 UIViews 在屏幕上不断移动。 使用UICollisionBehavior我可以防止视图相互碰撞，但我需要它们穿过屏幕的边缘（顶部、左侧、右侧、底部）。 在下面的这个例子中，一旦它们碰到屏幕的底部边缘，它们就会相互弹开，然后最终就坐在那里。 我试图对 UIViews 进行子类化，并查看冲突是否仅适用于子类类型，但这不起作用。

如何防止 UIView 相互碰撞，但仍让它们穿过屏幕边缘？

子类：

class CollisionView: UIView { // nothing special happens here except it's a subclass
}

代码：

lazy var redView: CollisionView = {
    let view = CollisionView()
    view.backgroundColor = .red
    return view
}()

lazy var blueView: CollisionView = {
    let view = CollisionView()
    view.backgroundColor = .blue
    return view
}()

lazy var yellowView: CollisionView = {
    let view = CollisionView()
    view.backgroundColor = .yellow
    return view
}()

lazy var purpleView: CollisionView = {
    let view = CollisionView()
    view.backgroundColor = .purple
    return view
}()

lazy var greenView: CollisionView = {
    let view = CollisionView()
    view.backgroundColor = .green
    return view
}()

var arr = [CollisionView]()

var animator: UIDynamicAnimator!
var gravity: UIGravityBehavior!
var collider: UICollisionBehavior!
var bouncingBehavior  : UIDynamicItemBehavior!

override func viewDidLoad() {
    super.viewDidLoad()
    view.backgroundColor = .white
    
    addSubViews()
    
    addAnimatorAndBehaviors()
}

func addAnimatorAndBehaviors() {
    
    animator = UIDynamicAnimator(referenceView: self.view)
    
    gravity = UIGravityBehavior(items: arr)
    animator.addBehavior(gravity)
    
    collider = UICollisionBehavior(items: arr)
    collider.translatesReferenceBoundsIntoBoundary = true
    animator.addBehavior(collider)
    
    bouncingBehavior = UIDynamicItemBehavior(items: arr)
    bouncingBehavior.elasticity = 0.75
    animator.addBehavior(bouncingBehavior)
}

func addSubViews() {
    
    let size = CGSize(width: 50, height: 50)
    
    redView.frame = CGRect(origin: view.center, size: size)
    blueView.frame = CGRect(origin: view.center, size: size)
    yellowView.frame = CGRect(origin: view.center, size: size)
    purpleView.frame = CGRect(origin: view.center, size: size)
    greenView.frame = CGRect(origin: view.center, size: size)
    
    view.addSubview(redView)
    view.addSubview(blueView)
    view.addSubview(yellowView)
    view.addSubview(purpleView)
    view.addSubview(greenView)
    
    arr = [redView, blueView, yellowView, purpleView, greenView]
}

Answer 1

很容易解决，我只需要添加：

collider.collisionMode = .items

CollisionView 子类是不必要的