Assigning SCNScene to SCNView - found nil while unwrapping Optional value - swift

Question

Recently, I decided to apply my previous knowledge in C++ and Python to learning Swift. After which, I decided to see what I could do with the SceneKit framework. After hours of checking through the documentation, and consulting a tutorial, I have to wonder what's going wrong with my code:
class GameViewController: UIViewController {
var gameView:SCNView!
var gameScene:SCNScene!
var cameraNode:SCNNode!
override func viewDidLoad() {
super.viewDidLoad()
initScene()
initView()
initCamera()
}
func initView() {
//initialize the game view - this view holds everything else in the game!
gameView = self.view as! SCNView
//allow the camera to move to gestures - mainly for testing purposes
gameView.allowsCameraControl = true
//use default lighting while still practicing
gameView.autoenablesDefaultLighting = true
}
func initScene() {
//initialize the scene
gameScene = SCNScene()
//set the scen in the gameView object to the scene created by this function
gameView.scene = gameScene
}
func initCamera() {
//create a node that will become the camera
cameraNode = SCNNode()
//since a node can be any object in the scene, this needs to be set up as a camera
cameraNode.camera = SCNCamera()
cameraNode.position = SCNVector3 (x:0, y:5, z:15)
}
}
After more checking through the documentation and making sure that I was now copying from the tutorial directly to get it to work, I still have no luck with this. According to a lot of the other questions I found here on StackOverflow, it looks like it has something to do with the forced unwrapping, the exclamation points, but I'm not exactly sure why that is.
I've probably been staring the answer in the face combing through this documentation, but I'm not quite seeing what the problem is.
Also, apologies if my comments are a bit long and/or distracting.

Answer 1

You have the following problems:
1) you should re-order the initializations in your viewDidLoad, doing so:
initView() // must be initialized before the scene
initScene() // you have been crashing here on getting `gameView.scene`, but gameView was nil
initCamera()
2) cameraNode is not attached on the rootNode, so you may add the following code at the end of initCamera:
gameScene.rootNode.addChildNode(cameraNode)