UIKitDynamics下的多手势问题

func handleAttachmentGesture(_ sender: UIPanGestureRecognizer) {

    let location = sender.location(in: emojiSuperView!)

    let boxLocation = sender.location(in: self)

    switch sender.state {

    case .began:

        print("Your touch start position is \(location)")

        print("Start location in image is \(boxLocation)")



        animator.removeAllBehaviors()



        let centerOffset = UIOffset(horizontal: boxLocation.x - self.bounds.midX, vertical: boxLocation.y - self.bounds.midY)

        attachmentBehavior = UIAttachmentBehavior(item: self, offsetFromCenter: centerOffset, attachedToAnchor: location)

        animator.addBehavior(attachmentBehavior)

    case .ended:

        print("Your touch end position is \(location)")

        print("End location in image is \(boxLocation)")



        animator.removeAllBehaviors()



        // 1

        let velocity = sender.velocity(in: emojiSuperView!)

        let magnitude = sqrt((velocity.x * velocity.x) + (velocity.y * velocity.y))



        if magnitude > ThrowingThreshold {

            // 2

            let pushBehavior = UIPushBehavior(items: [self], mode: .instantaneous)

            pushBehavior.pushDirection = CGVector(dx: velocity.x / 10, dy: velocity.y / 10)

            pushBehavior.magnitude = magnitude / ThrowingVelocityPadding



            self.pushBehavior = pushBehavior

            animator.addBehavior(pushBehavior)



            // 3

            let angle = Int(arc4random_uniform(20)) - 10



            itemBehavior = UIDynamicItemBehavior(items: [self])

            itemBehavior.friction = 0.2

            itemBehavior.allowsRotation = true

            itemBehavior.addAngularVelocity(CGFloat(angle), for: self)

            animator.addBehavior(itemBehavior)

        }

    default:

        attachmentBehavior.anchorPoint = sender.location(in: emojiSuperView!)

        break

    }

}





func recognizePinchGesture(sender: UIPinchGestureRecognizer)

{

    weak var dynamicItem: UIDynamicItem?

    // whatever your item is, probably a UIView

    dynamicItem = self

    let behavior = UIGravityBehavior(items: [dynamicItem!])

    let animator = UIDynamicAnimator(referenceView: emojiSuperView!)

    // or however you're getting your animator

    animator.addBehavior(behavior)

    sender.view!.transform = sender.view!.transform.scaledBy(x: sender.scale, y: sender.scale)

    animator.updateItem(usingCurrentState: self)

    self.animator.updateItem(usingCurrentState: self)

    sender.scale = 1

}