Sample UIKit Dynamics w rotated view

DynamicsDemo.swift

class ViewController: UIViewController {
    lazy var animator = UIDynamicAnimator(referenceView: view)

    override func viewDidLoad() {
        super.viewDidLoad()

        let animatedView = UIView(frame: CGRect(x: 120, y: 100, width: 50, height: 50))
        animatedView.transform = CGAffineTransform(rotationAngle: .pi / 4)
        animatedView.backgroundColor = .blue

        let fixedView = UIView(frame: CGRect(x: 110, y: 300, width: 20, height: 20))
        fixedView.backgroundColor = .red

        view.addSubview(animatedView)
        view.addSubview(fixedView)

        let collision = UICollisionBehavior(items: [animatedView, fixedView])
        collision.translatesReferenceBoundsIntoBoundary = true
        animator.addBehavior(collision)

        let gravity = UIGravityBehavior(items: [animatedView])
        gravity.magnitude = 0.1
        animator.addBehavior(gravity)

        let attachment = UIAttachmentBehavior(item: fixedView, attachedToAnchor: fixedView.center)
        animator.addBehavior(attachment)

        let configuration = UIDynamicItemBehavior(items: [fixedView])
        configuration.allowsRotation = false
        animator.addBehavior(configuration)
    }
}