Here’s an F# iOS 8 Scene Kit port of the C# code from the Xamarin blog, ported with some help from Larry O’Brien.

namespace FSHelloSceneKit
    
open System
open MonoTouch.UIKit
open MonoTouch.Foundation
open MonoTouch.SceneKit
 
type FSHelloSceneKitViewController () =
    inherit UIViewController()
   
    let CreateDiffuseLightNode (color: UIColor, position: SCNVector3, lightType: NSString): SCNNode = 
        new SCNLight ( Color = color, LightType = lightType )
        |> fun lightNode -> new SCNNode ( Light = lightNode, Position = position )
 
    override this.ViewDidLoad () =
        let scene = new SCNScene ()
     
        let view = new SCNView (this.View.Frame, Scene = scene, AutoresizingMask = UIViewAutoresizing.All, AllowsCameraControl = true)
 
        new SCNCamera (XFov = 40.0, YFov = 40.0)
        |> fun c -> new SCNNode (Camera = c, Position = new SCNVector3(0.0F, 0.0F, 40.0F))
        |> scene.RootNode.AddChildNode
 
        let material = new SCNMaterial ()
        material.Diffuse.Contents <- UIImage.FromFile ("monkey.png")
        material.Specular.Contents <- UIColor.White
 
        new SCNNode( Geometry = SCNSphere.Create(10.0F), Position = new SCNVector3(0.0F, 0.0F, 0.0F) )
        |> fun node -> node.Geometry.FirstMaterial <- material; node
        |> scene.RootNode.AddChildNode
 
        new SCNLight ( LightType = SCNLightType.Ambient, Color = UIColor.Purple)
        |> fun lightNode -> new SCNNode ( Light = lightNode )
        |> scene.RootNode.AddChildNode
 
        [|
            ( UIColor.Blue, new SCNVector3 (-40.0F, 40.0F, 60.0F) );
            ( UIColor.Yellow, new SCNVector3 (20.0F, 20.0F, -70.0F) );
            ( UIColor.Red, new SCNVector3 (20.0F, -20.0F, 40.0F) );
            ( UIColor.Green, new SCNVector3 (20.0F, -40.0F, 70.0F) )
        |]
        |> Seq.map (fun (color, pos) -> CreateDiffuseLightNode(color, pos, SCNLightType.Omni))
        |> Seq.iter scene.RootNode.AddChildNode
 
        this.View.Add(view)

You can read more about Scene Kit on the Xamarin blog.