title: How can I know the values in CABasicAnimation keyPath
body: <p>I find some code like this:</p>
  
  <pre><code>CABasicAnimation *anim = [CABasicAnimation animation];
  anim.keyPath = @"transform.scale";
  anim.fromValue = [NSNumber numberWithFloat:1.0];
  anim.toValue = [NSNumber numberWithFloat:0];
  anim.removedOnCompletion = NO;
  anim.fillMode = kCAFillModeBoth;
  anim.delegate = self;
  [self.view.layer addAnimation:anim forKey:@"scaleOut"];
  </code></pre>
  
  <p>and</p>
  
  <pre><code>anim.keyPath = @"transform.rotation.x";
  </code></pre>
  
  <p>As far as I know, keyPath is a chained method invoke. "transform.scale" for CALayer is aLayer.transform.scale. "transform" is a property of CALayer, "scale" is a 'property' of transform. But property transform in CALayer is CATransform3D.</p>
  
  <p>There is no property named "scale" or "rotation" in CATransform3D. </p>
  
  <p>My Question is:
  How "scale" and "rotation" are identified by keyPath ?</p>