You can place an SKCameraNode into an SKScene to define which part of the scene is shown in the SKView. Think of the SKScene as a 2D world with a camera floating above it: the SKView will show what the camera 'sees'.
E.g. the camera could be attached to the main character's sprite to follow the action of a scrolling game.
The SKCameraNode has four parameters that define what part of the scene is shown:
The following code assumes an SKView called skView already exists (e.g. as defined in Create a Full Screen SKView using Interface Builder) and a subclass of SKScene called GameView has been defined. This example just sets the camera's initial position, you would need to move the camera (in the same way as you would other SKSpriteNodes in the scene) to scroll your view:
In Swift 3:
let sceneSize = CGSize(width:1000, height:1000)
let scene = GameScene(size: sceneSize)
scene.scaleMode = .aspectFill
let camera = SKCameraNode()
camera.position = CGPointM(x:500, y:500)
camera.xScale = 1
camera.yScale = 1
camera.zRotation = 3.14
scene.addChild(camera)
scene.camera = camera
skView.presentScene(scene)