title: What kind of value is keyTime in an CAKeyFrameAnimation?
body: <p>For example I have this CAKeyFrameAnimation:</p>
  
  <pre><code>CALayer* theLayer = myView.layer;
      CAKeyframeAnimation* animation;
      animation = [CAKeyframeAnimation animationWithKeyPath:@"transform.rotation.z"];
  
      animation.duration = 1.6;
      //animation.cumulative = YES;
      animation.repeatCount = 1;
      animation.removedOnCompletion = NO;
      animation.fillMode = kCAFillModeForwards;
  
      animation.values = [NSArray arrayWithObjects:
                          [NSNumber numberWithFloat:0.0 * M_PI],
                          [NSNumber numberWithFloat:(15.0/180.0) * M_PI],
                          [NSNumber numberWithFloat:(30.0/180.0) * M_PI], // animation stops here...
                          [NSNumber numberWithFloat:(45.0/180.0) * M_PI], // ignored!
                          [NSNumber numberWithFloat:(190.0/180.0) * M_PI], nil]; // ignored!
  
      animation.keyTimes = [NSArray arrayWithObjects:
                            [NSNumber numberWithFloat:0.0],
                            [NSNumber numberWithFloat:0.2],
                            [NSNumber numberWithFloat:0.4], // ignored!
                            [NSNumber numberWithFloat:0.8], // ignored!
                            [NSNumber numberWithFloat:1.6], nil]; // ignored!
  
      animation.timingFunctions = [NSArray arrayWithObjects:
                                   [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear], 
                                   [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear],
                                   [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear],
                                   [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear],
                                   [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear], nil];
  
      [theLayer addAnimation:animation forKey:@"transform.rotation.z"];
  </code></pre>
  
  <p>What I don't get is: </p>
  
  <p>A) are key time values absolute passed time since the animation has started?</p>
  
  <p>B) are key time values just saying how much time to use for this particular key frame?</p>