andresbrun

import UIKit
import PlaygroundSupport

let containerView = UIView(frame: CGRect(x: 0.0, y: 0.0, width: 320.0, height: 480.0))

// Play with containerView
let targetView = UIView(frame: CGRect(x: containerView.bounds.midX, 
                                      y: containerView.bounds.midY, 
                                      width: 50.0, 
                                      height: 50.0))

andresbrun

let animator = UIDynamicAnimator(referenceView: containerView)

let gravityBehaviour = UIGravityBehavior(items: [targetView])
gravityBehaviour.magnitude = 1.0 // gravity on earth
animator.addBehavior(gravityBehaviour)

andresbrun

let pushContinousBehaviour = UIPushBehavior(items: [targetView], mode: .continuous)
animator.addBehavior(pushContinousBehaviour)

// Using pushDirection
pushContinousBehaviour.pushDirection = CGVector(dx: 50, dy: 0)

// Using magnitude and angle
pushContinousBehaviour.magnitude = 50
pushContinousBehaviour.angle = 0

andresbrun

let gravityBehaviour = UIGravityBehavior(items: [targetView])
animator.addBehavior(gravityBehaviour)

// It can be defined with
gravityBehaviour.magnitude = 1.0 // Gravity on earth
gravityBehaviour.angle = .pi / 2.0 // downward direction

// Or
gravityBehaviour.gravityDirection = CGVector(dx: 0.0, dy: 1.0) // Gravity on earth

andresbrun

let snapBehaviour = UISnapBehavior(item: targetView, snapTo: CGPoint(x: 100, y: 100))
animator.addBehavior(snapBehaviour)

// You can configure the oscillation of the item when it has to go to the snap point
snapBehaviour.damping = 0.5 // Medium oscillation 

andresbrun

let collisionBehaviour = UICollisionBehavior(items: [targetView])
animator.addBehavior(collisionBehaviour)

// Collision with bounds of superview
collisionBehaviour.setTranslatesReferenceBoundsIntoBoundary(with: .zero)

// Collision with custom boundaries
collisionBehaviour.addBoundary(withIdentifier: "barrier" as NSCopying, 
                               for: UIBezierPath(ovalIn: containerView.bounds))

andresbrun

// Dragging an element with a PanGestureRecognizer for instance
let dragAttachmentBehaviour = UIAttachmentBehavior(item: targetView,
                                                   offsetFromCenter: offsetFromCenter,
                                                   attachedToAnchor: dragLocation)

// Attaching two box in a chain
let boxAttachmentBehaviour = UIAttachmentBehavior(item: box1, 
                                                  offsetFromCenter: UIOffset(horizontal: 0, vertical: box1.bounds.midY), 
                                                  attachedTo: box2, 
                                                  offsetFromCenter: UIOffset(horizontal: 0, vertical: -box2.bounds.midY))

andresbrun

import UIKit
import XCPlayground

public class DynamicModalBehaviour: NSObject {
    private var animator: UIDynamicAnimator?
    private var dragAttachmentBehaviour: UIAttachmentBehavior!
    private var itemsCollisionBehaviour: UICollisionBehavior!
    private var modalViewExitBehaviour: UIDynamicItemBehavior!
    private var itemsAttachmentBehaviours: [UIAttachmentBehavior]!
    private var snapBehaviours: [UISnapBehavior]!

andresbrun

let slidingBehaviour = UIAttachmentBehavior.slidingAttachment(with: targetView, 
                                                              attachedTo: draggableView, 
                                                              attachmentAnchor: targetView.center, 
                                                              axisOfTranslation: CGVector(dx: 1, dy: 0))
animator.addBehavior(slidingBehaviour)

andresbrun

let dynamicBehaviour = UIDynamicItemBehavior(items: balls)
dynamicBehaviour.elasticity = 0.8
dynamicBehaviour.friction = 5.0
animator.addBehavior(dynamicBehaviour)