SKPhysics with Swift and SpriteKit - ios

Question

I am trying to create a iOS game using Swift Programming Language.
I want to use swipe gestures on the screen to make the character (player) move up, down, left and right
So far so good. But I want some physics. I want the player to collide with the edges of the screen. (and later I want it to collide with other stuff, but I need to know the code first ;)
QUESTION: How do I identify a collision between 2 objects (player and edge of screen)
import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate {
var player:SKSpriteNode = SKSpriteNode()
let moveUp = SKAction.moveByX(0, y:2000, duration:10.0) //it is set to 2000 because I want to see if it collides with the edge of the screen
let moveDown = SKAction.moveByX(0, y: -200, duration: 2.0)
// Define the bitmasks identifying various physics objects
let worldCategory:UInt32 = 0x1 << 0
let playerCategory:UInt32 = 0x1 << 1
override func didMoveToView(view: SKView) {
}
override init(size:CGSize) {
super.init(size: size)
self.backgroundColor = SKColor.whiteColor()
player = SKSpriteNode(imageNamed: "Kundvagn1")
player.position = CGPointMake(self.frame.size.width/2, player.size.height/2 + 20)
self.addChild(player)
player.runAction(moveUp)
self.physicsWorld.gravity = CGVectorMake(0, 0)
self.physicsWorld.contactDelegate = self
player.physicsBody = SKPhysicsBody(rectangleOfSize: player.size)
player.physicsBody?.dynamic = true //I dont think the question marks should be there, but Xcode doesn´t accept the code if there is no question marks there
player.physicsBody?.categoryBitMask = playerCategory
player.physicsBody?.contactTestBitMask = worldCategory
player.physicsBody?.collisionBitMask = 0
player.physicsBody?.usesPreciseCollisionDetection = true
}
func didBeginContact(contact: SKPhysicsContact!) {
println("Collision")
}

Answer 1

Assuming that you want the left and right edges to block, simply add two SKShapeNode rectangular objects to your scene, set their heights to the screen height, and place them just beyond the left and right edges of the screen. Set up their physics bodies and you should be good to go.
If you want all the edges of the screen to be boundaries, you need to setup a line-based physics body for your scene, as detailed here: Add boundaries to an SKScene

Answer 2

I added this in case you need a code example to jonogilmour's instructions . Turn on the ShowsPhysics = true in your viewController to see physics. Both sides should be blue. If you want a contact notification of course you would add to this code with your bit mask stuff. Hope this helps!
var leftEdge = SKNode()
leftEdge.physicsBody = SKPhysicsBody(edgeFromPoint: CGPointZero, toPoint: CGPointMake(0.0, self.size.height))
leftEdge.position = CGPointZero;
self.addChild(leftEdge)
var rightEdge = SKNode()
rightEdge.physicsBody = SKPhysicsBody(edgeFromPoint: CGPointZero, toPoint: CGPointMake(0.0, self.size.height))
rightEdge.position = CGPointMake(self.size.width, 0.0);
self.addChild(rightEdge)