title: How do I address the “There was a problem running this page” message in Swift Playgrounds?
body: <p>I am trying to make something with SceneKit for the WWDC Student Challenge, which requires my project be in a Swift playground.  I keep getting the message that says “There was a problem running this page.”  It offers no error messages.  It just suggests that check my code or start over.  I have tried removing pieces of code individually, but I cannot locate the source of this issue.  I have also tried running it in man Xcode playground, which offered the warning of, and I quote, “The playground could not continue running because the playground source did”.  I am stuck.  What is wrong with my code.</p>
  <pre><code>import UIKit
  import SceneKit
  import QuartzCore 
  import PlaygroundSupport
  
  class GameScene: UIViewController, SCNSceneRendererDelegate {
      var primaryView: SCNView!
      var primaryScene: SCNScene!
      var cameraNode: SCNNode!
      
      override func viewDidLoad() {
          sceneAndViewInit()
          cameraInit()
          createGround()
          moonInit()
      }
      
      func createGround() {
          var ground = SCNBox(width: 200, height: 1, length: 200, chamferRadius: 0)
          var groundPhysicsShape = SCNPhysicsShape(geometry: ground, options: nil) 
          var groundNode = SCNNode(geometry: ground)
          ground.firstMaterial?.diffuse.contents = UIColor.orange
          ground.firstMaterial?.specular.contents = UIColor.white
          groundNode.position = SCNVector3(0, -6, 0)
          groundNode.physicsBody = SCNPhysicsBody(type: .static, shape: groundPhysicsShape)
          primaryScene.rootNode.addChildNode(groundNode)
      }
      
      func sceneAndViewInit() {
          primaryView = SCNView(frame: CGRect(x: 0, y: 0, width: 500, height: 300))
          primaryView.allowsCameraControl = true
          primaryView.autoenablesDefaultLighting = true
          
          primaryScene = SCNScene()
          
          primaryView.scene = primaryScene
          primaryView.isPlaying = true
      }
      
      func cameraInit() {
          var cameraNode = SCNNode()
          cameraNode.camera = SCNCamera()
          cameraNode.position = SCNVector3(x: 0, y: 0, z: 2)
          cameraNode.camera?.fieldOfView = 65
          cameraNode.camera?.wantsHDR = false
          primaryScene.rootNode.addChildNode(cameraNode)
      }
      
      func moonInit() {
          let moonScene = SCNScene(named: &quot;Moon.scn&quot;)
          var moonNode = moonScene?.rootNode.childNode(withName: &quot;Sphere&quot;, recursively: true)
          var moonPhysicsShape = SCNPhysicsShape(node: moonNode!, options: nil)
          moonNode?.position = SCNVector3(0, 0, 0)
          moonNode?.scale = SCNVector3(1, 1, 1)
          moonNode?.name = &quot;Moon&quot;
          moonNode?.physicsBody = SCNPhysicsBody(type: .static, shape: moonPhysicsShape)
          primaryScene.rootNode.addChildNode(moonNode!)
      }
      
      func renderer(_ aRenderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
          print(time)
      }
  }
  
  let gameScene = GameScene()
  PlaygroundPage.current.liveView = gameScene
  </code></pre>
  <p>(“Moon.scn” is a file that I have in the resources/files section along with its texture, and I still have the issue without any of the moon related code.)</p>