ios - UICollisionBehaviorDelegate方法未调用

我开发了一个应用程序，并使用UIKitDynamics实现了碰撞检测。

碰撞检测正在运行。但是以某种方式没有调用UICollisionBehaviorDelegate方法。
没有显示警告或错误。

我创建了一个示例项目来演示该问题:

  import UIKit

  class ViewController: UIViewController {
    private var dynamicAnimator: UIDynamicAnimator?

    override func viewDidLoad() {
      super.viewDidLoad()
      // Do any additional setup after loading the view, typically from a nib.
    }

    override func viewDidAppear(_ animated: Bool) {
      super.viewDidAppear(animated)

      self.initPhysics()
    }

    fileprivate var initalized = false
    fileprivate func initPhysics() {
      if initalized {
        return
      }
      initalized = true

      let physicsView = UIView(frame: view.bounds.insetBy(dx: 40, dy: 40))
      physicsView.backgroundColor = UIColor.black

      self.dynamicAnimator = UIDynamicAnimator(referenceView: physicsView)

      physicsView.isUserInteractionEnabled = false
      view.addSubview(physicsView)

      //Create ball
      let frame = CGRect(x: 0, y: 0, width: 40, height: 40)

      let rect = UIView(frame: frame)
      rect.backgroundColor = UIColor.red
      physicsView.addSubview(rect)

      let behavior = UIDynamicItemBehavior(items: [rect])
      behavior.elasticity = 1.0
      behavior.resistance = 0.0
      behavior.friction = 0.0
      behavior.allowsRotation = false
      self.dynamicAnimator?.addBehavior(behavior)

      //collision behavior setup
      let collisionBehavior = UICollisionBehavior(items: [rect])
      collisionBehavior.collisionDelegate = self
      collisionBehavior.setTranslatesReferenceBoundsIntoBoundary(with: .zero)
      collisionBehavior.collisionMode = .everything
      self.dynamicAnimator?.addBehavior(collisionBehavior)

      //Push ball
      let pushBehavior = UIPushBehavior(items: [rect], mode: UIPushBehaviorMode.instantaneous)
      pushBehavior.active = true
      pushBehavior.pushDirection = CGVector(dx: 0.5, dy: 0.5)
      self.dynamicAnimator?.addBehavior(pushBehavior)
    }
  }

  extension ViewController: UICollisionBehaviorDelegate {
    // DELEGATE METHODS NOT CALLED
    func collisionBehavior(_ behavior: UICollisionBehavior,
                           beganContactFor item: UIDynamicItem,
                           withBoundaryIdentifier identifier: NSCopying?,
                           at p: CGPoint) {
      print("began contact boundary")
    }

    func collisionBehavior(_ behavior: UICollisionBehavior,
                           endedContactFor item: UIDynamicItem,
                           withBoundaryIdentifier identifier: NSCopying?) {
      print("contact boundary ended")
    }

    func collisionBehavior(_ behavior: UICollisionBehavior,
                           endedContactFor item1: UIDynamicItem,
                           with item2: UIDynamicItem) {

      print("contact item ended")
    }

    func collisionBehavior(_ behavior: UICollisionBehavior,
                           beganContactFor item1: UIDynamicItem,
                           with item2: UIDynamicItem,
                           at p: CGPoint) {
      print("began contact item")
    }
  }

基本SDK:iOS 11.2，Xcode版本9.2(9C40b)

感谢您的帮助!

最佳答案

那不是它的工作方式(可悲)。您的碰撞行为中只有一个项目，您要它检测与什么碰撞？如果添加了第二项，则将看到该委托被调用。

真正的问题是为什么？好吧，碰撞检测一个项目的框架是否与另一个项目的框架相交..如果它满足了您的要求(rect是physicsView的子级)，那么它总是会发生碰撞(这不是您想要的)。

由于您的physicsView不属于碰撞行为，因此您什么也没得到。.您告诉它将项目限制在其范围内(setTranslatesReferenceBoundsIntoBoundary在添加到行为本身的项目上起作用)，但不检测与范围的碰撞。例如，如果项目在physicsView之外，则无法进入。如果在内部，则无法退出。但是每个说话不会将其计为一次碰撞(否则它总是会发生碰撞)。

为了检测rect和physicsView之间的冲突，您需要为physicsView提供一些物理属性。.现在，它只是常规的UIView(参考视图)。

解决必须赋予其物理属性的另一种方法是为其添加边界:

collisionBehavior.addBoundary(withIdentifier: "PhysicsViewBoundary" as NSString, for: UIBezierPath(rect: physicsView.bounds))

现在它将调用:

func collisionBehavior(_ behavior: UICollisionBehavior,
                       beganContactFor item: UIDynamicItem,
                       withBoundaryIdentifier identifier: NSCopying?,
                       at p: CGPoint) {
    print("began contact boundary")
}

func collisionBehavior(_ behavior: UICollisionBehavior,
                       endedContactFor item: UIDynamicItem,
                       withBoundaryIdentifier identifier: NSCopying?) {
    print("contact boundary ended")
}