title: iPhone - setValue:forkey: not documented
body: <p>I have these lines in my code :</p>
  
  <pre><code>[defaults setValue:someValue forKey:@"someValue"];
  [animationGroup setValue:@"someValue" forKey:@"someValue"];  // CAAnimationGroup
  NSString* animName = [theAnimation valueForKey:@"someValue"]; // CAAnimation
  </code></pre>
  
  <p>But reading the Apple Reference Documentation :</p>
  
  <ul>
  <li><a href="https://developer.apple.com/library/IOs/#documentation/Cocoa/Reference/Foundation/Classes/NSUserDefaults_Class/Reference/Reference.html" rel="nofollow">https://developer.apple.com/library/IOs/#documentation/Cocoa/Reference/Foundation/Classes/NSUserDefaults_Class/Reference/Reference.html</a>  </li>
  <li><a href="https://developer.apple.com/library/IOs/#documentation/GraphicsImaging/Reference/CAAnimationGroup_class/Introduction/Introduction.html" rel="nofollow">https://developer.apple.com/library/IOs/#documentation/GraphicsImaging/Reference/CAAnimationGroup_class/Introduction/Introduction.html</a></li>
  <li><a href="https://developer.apple.com/library/IOs/#documentation/GraphicsImaging/Reference/CAAnimation_class/Introduction/Introduction.html#//apple_ref/occ/cl/CAAnimation" rel="nofollow">https://developer.apple.com/library/IOs/#documentation/GraphicsImaging/Reference/CAAnimation_class/Introduction/Introduction.html#//apple_ref/occ/cl/CAAnimation</a></li>
  </ul>
  
  <p>I don't see any reference to these methods, even parsing hierarchy or conformed protocols. From where do they come ? Is their use allowed ?</p>