title: SceneKit - Textures not properly displayed
body: <p>I have a cube (rounded) and want to display a texture on one of it's side. I can access the material on that side with:</p>
  
  <pre><code>var tex1: SCNMaterial! = cube.geometry?.materialWithName("_1")!
  </code></pre>
  
  <p>I then set it's image contents:</p>
  
  <pre><code>tex1.diffuse.contents = "cube1"
  </code></pre>
  
  <p>This then looks like this:</p>
  
  <p><img src="https://i.stack.imgur.com/OPgFu.png" alt="cube with texture"></p>
  
  <p>This shows me that it does work, but the white part is not in the center as 
  it should be. (The image I am using has the white part in the center.)
  <br>
  I tried to use offset to move the image around on the surface, I would like scale it as well. I tried it like this:</p>
  
  <pre><code>tex1.diffuse.contents.offset = SCNVector3Make(20, 0, 0)
  </code></pre>
  
  <p>That gives me errors: it says it cannot assign the result of that expression. (I also tried <code>contentMode</code>, same error, I think because these are for UI, not SCN)</p>
  
  <p><strong>Questions</strong></p>
  
  <ol>
  <li>Does anyone know what I can do? <br></li>
  <li>Maybe offset is not the way to go? <br></li>
  <li>How can I scale the image?</li>
  </ol>