Quick demo of 3d drawing in ARKit using metal + SceneKit.
NOTE: This is experimental code! ..I'm just learning swift.
Also note: this demo is pretty trivial to accomplish in Unity with the ARKit plugin (https://forum.unity3d.com/threads/arkit-support-for-ios-via-unity-arkit-plugin.474385/ https://www.assetstore.unity3d.com/en/#!/content/92515 ). This demo was more to see if metal drawing could be layered on top of scenekit.