geometry of the node from dae file is nil
<p>I've made 3d model with blender and I want to use it in scene kit.</p>

<pre><code>var platform = SCNNode();
let dae = SCNScene(named:"platform.dae");
platform = dae!.rootNode;
platform.position = SCNVector3(x: 0,y: 0,z:0);
if platform.geometry == nil {
    print("geo is nil.")
}
platform.geometry?.firstMaterial?.diffuse.contents = "wood.png";
platform.geometry?.firstMaterial?.diffuse.wrapS = SCNWrapMode.Repeat
platform.geometry?.firstMaterial?.diffuse.wrapT = SCNWrapMode.Repeat
platform.physicsBody = SCNPhysicsBody(type: SCNPhysicsBodyType.Static, shape: SCNPhysicsShape(node: platform, options: nil));
scene.rootNode.addChildNode(platform);
</code></pre>

<p>It always prints out "geo is nil". So I can't make a physics body for the model. Can anyone tell me why does this happen?</p>