import UIKit

class EscapeViewController: UIViewController {

    var animator: UIDynamicAnimator!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let square = UIView(frame: CGRect(x: 150, y: 150, width: 50, height: 50))
        square.backgroundColor = UIColor.gray
        view.addSubview(square)
        
        animator = UIDynamicAnimator(referenceView: view)
        let gravity = UIGravityBehavior(items: [square])
        animator.addBehavior(gravity)
        
        let push = UIPushBehavior(items: [square], mode: .instantaneous)
        push.angle = 2.0
        push.magnitude = 2.0
        animator.addBehavior(push)
        
        let collision = UICollisionBehavior(items: [square])
        collision.translatesReferenceBoundsIntoBoundary = true
        animator.addBehavior(collision)
    }
}