How can I change a SCNView back to a UIView? - ios

Question

I am trying to use code from an example of a Game with Xcode as a Swift Playground. The code works perfectly in the Xcode version, but in the playground, I get the error:
Could not cast value of type 'UIView' (0x114debe38) to 'SCNView' (0x12521d3d0).
The type of class is set to be of type UIViewController, so I am not sure why this does not work in only the playground. II have the same files in both the app and the playground.
I have already looked at this question, but the method seems to be built in already.
I also tried to cast it back to a UIView if it was a SCNView and I also tried making a new view, adding a subview as a SCNView to it, and then setting the final view as the new view. None of my attempts worked.
class GameScene: UIViewController {
let finalView = UIView()
override func viewDidLoad() {
super.viewDidLoad()
// create a new scene
let scene = SCNScene(named: "art.scnassets/ship.scn")!
// create and add a camera to the scene
let cameraNode = SCNNode()
cameraNode.camera = SCNCamera()
scene.rootNode.addChildNode(cameraNode)
// place the camera
cameraNode.position = SCNVector3(x: 0, y: 0, z: 15)
cameraNode.rotation = SCNVector4(0, 0, 0, 30)
// create and add a light to the scene
let lightNode = SCNNode()
lightNode.light = SCNLight()
lightNode.light!.type = .omni
lightNode.position = SCNVector3(x: 0, y: 10, z: 10)
scene.rootNode.addChildNode(lightNode)
// create and add an ambient light to the scene
let ambientLightNode = SCNNode()
ambientLightNode.light = SCNLight()
ambientLightNode.light!.type = .ambient
ambientLightNode.light!.color = UIColor.darkGray
scene.rootNode.addChildNode(ambientLightNode)
// retrieve the shark node
let shark = scene.rootNode.childNode(withName: "ship", recursively: true)!
// animate the 3d object
//shark.runAction(SCNAction.repeatForever(SCNAction.rotateBy(x: 0, y: 2, z: 0, duration: 1)))
// retrieve the SCNView
let scnView = self.view as! SCNView
// set the scene to the view
scnView.scene = scene
// allows the user to manipulate the camera
scnView.allowsCameraControl = true
// show statistics such as fps and timing information
scnView.showsStatistics = true
// configure the view
scnView.backgroundColor = UIColor.black
// add a tap gesture recognizer
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleTap(_:)))
scnView.addGestureRecognizer(tapGesture)
}
#objc
func handleTap(_ gestureRecognize: UIGestureRecognizer) {
// retrieve the SCNView
let scnView = self.view as! SCNView
finalView.addSubview(scnView)
// check what nodes are tapped
let p = gestureRecognize.location(in: scnView)
let hitResults = scnView.hitTest(p, options: [:])
// check that we clicked on at least one object
if hitResults.count > 0 {
// retrieved the first clicked object
let result = hitResults[0]
// get its material
let material = result.node.geometry!.firstMaterial!
// highlight it
SCNTransaction.begin()
SCNTransaction.animationDuration = 0.5
// on completion - unhighlight
SCNTransaction.completionBlock = {
SCNTransaction.begin()
SCNTransaction.animationDuration = 0.5
material.emission.contents = UIColor.black
SCNTransaction.commit()
}
material.emission.contents = UIColor.red
SCNTransaction.commit()
}
}
override var shouldAutorotate: Bool {
return true
}
override var prefersStatusBarHidden: Bool {
return true
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
if UIDevice.current.userInterfaceIdiom == .pad {
return .allButUpsideDown
} else {
return .all
}
}
}
PlaygroundSupport.PlaygroundPage.current.liveView = GameScene()
What this should show up is a 3D Model and a camera that can pan around it by touch on a mobile device.

Answer 1

In your example the UIViewController view was probably set to an SCNView in interface builder. If you're not using a nib you can do this by overriding loadView.
override func loadView() {
let scnView = SCNView(frame: UIScreen.main.bounds, options: nil)
self.view = scnView
}