Import 3D model in SceneKit - Swift - swift

Question

I'm creating a game where the player can control a cube.
He could buy new cubes.
I created the basic cube like that :
// MAIN CUBE
mainCubeGeometry = SCNBox(width: 0.2, height: 0.2, length: 0.2, chamferRadius: 0.0)
mainCubeGeometry.firstMaterial?.diffuse.contents = UIColor.redColor()
mainCubeNode = SCNNode(geometry: mainCubeGeometry)
mainCubeNode.position = SCNVector3(x: 0.0, y: 0.0, z: 0.0)
scene.rootNode.addChildNode(mainCubeNode)
I would like to know how use 3D models (dae) of cubes created on any software (SketchUp per exemple). I don't really understand how to load the 3D file when the scene is created (scene = SCNScene(named: "3d.scnassets/cube.dae")) because it is a scene, so it import a scene into my original scene, while I just want to import a 3D model in a node to use it like my basic cube.
Thanks for your help !

Answer 1

SCNScene(named:) returns an SCNNode with all of the objects from that DAE file as child nodes. Load the file, retrieve the bodies you're interested in, and add them to your scene's root node.
Here are a couple of snippets from the Fox sample app from WWDC 2015. The Character class has a node property initialized like this:
let characterScene = SCNScene(named: "game.scnassets/panda.scn")!
let characterTopLevelNode = characterScene.rootNode.childNodes[0]
node.addChildNode(characterTopLevelNode)
And then add the character to the scene like this:
// Add the character to the scene.
scene.rootNode.addChildNode(character.node)

Answer 2

SOLUTION
I found a solution on this post : How do you load a .dae file into an SCNNode in IOS SceneKit?
class func collada2SCNNode(filepath:String) -> SCNNode {
var node = SCNNode()
let scene = SCNScene(named: filepath)
var nodeArray = scene!.rootNode.childNodes
for childNode in nodeArray {
node.addChildNode(childNode as SCNNode)
}
return node
}
Use :
let myNode = collada2SCNNode("nodes.scnassets/node.dae")
scene.rootNode.addChildNode(myNode)