physics in playground

test.swift

// This code worked width Xcode 6 Beta 6

import SpriteKit
import XCPlayground

let width:CGFloat = 480.0
let height:CGFloat = 800.0
let canvasWidth: UInt32 = UInt32(width)
let canvasHeight: UInt32 = UInt32(height)

let view:SKView = SKView(frame: CGRectMake(0, 0, width, height))
let scene:SKScene = SKScene(size: CGSizeMake(width, height))
scene.backgroundColor = SKColor(red: 0, green:0, blue:0, alpha:1)
scene.physicsWorld.gravity = CGVectorMake(0, -5)
view.presentScene(scene)

let physicsBody = SKPhysicsBody(edgeLoopFromRect:CGRect(x:0, y:0, width:width, height:height))
scene.physicsBody = physicsBody;

for var i = 0; i < 100; i++  {
    let shape = SKShapeNode(circleOfRadius:10)
    shape.fillColor = SKColor(red:0, green:0.5, blue:1.0, alpha:1.0)
    shape.lineWidth = 2
    shape.position = CGPoint(x:CGFloat(arc4random_uniform(canvasWidth)), y:CGFloat(canvasHeight - arc4random_uniform(200)))
    scene.addChild(shape)
    
    shape.physicsBody = SKPhysicsBody(circleOfRadius: shape.frame.size.width/2)
    shape.physicsBody.friction = 0.01
    shape.physicsBody.restitution = 0.95
    shape.physicsBody.mass = 1.0
    shape.physicsBody.allowsRotation = true
}

XCPShowView("my view", view)