title: Animation blocks in iOS using block objects?
body: <p>From the Apple documentation on animating property changes in a view,</p>
  
  <blockquote>
    <p>In order to animate changes to a property of the UIView class, you
    must wrap those changes inside an <strong>animation block</strong>. The term animation
    block is used in the generic sense to refer to any code that
    designates animatable changes. In iOS 4 and later, you create an
    animation block using block objects. In earlier versions of iOS, you
    mark the beginning and end of an animation block using special class
    methods of the UIView class. Both techniques support the same
    configuration options and offer the same amount of control over the
    animation execution. However, the block-based methods are preferred
    whenever possible.</p>
  </blockquote>
  
  <p>Other than the confusing terminology between an <em>animation block</em> and an objective-c <em>block object</em>, I am wondering what are some good resources and examples for using block objects to do animations with the UIView class? I have looked through the Apple documentation and also googled for some examples and could not find very many helpful resources. Also, what can we do to make sure that it is backwards compatible with devices earlier than iOS 4? I read somewhere that using a block object in earlier versions will cause a crash?</p>