title: Scrolling a patterned background on UIView
body: <p>I have a simple UIView which I'm filling with a patterned background, like this</p>
  
  <pre><code>    self.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"backgroundPattern"]];
  </code></pre>
  
  <p>I want to be able to manipulate the origin of the view by modifying its bounds property and have the background move with the change in origin (as if the background is fixed to the content, not floating behind it).  Is this possible?  Currently the background seems fixed to the view's frame instead of its bounds and the pattern doesn't scroll when the content scrolls.</p>
  
  <p>To change the origin I'm using a block animation like this</p>
  
  <pre><code>self.bounds = CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height);
  [UIView animateWithDuration:1. delay:0. options:UIViewAnimationOptionRepeat animations:^{
      self.bounds = CGRectMake(0, 100, self.bounds.size.width, self.bounds.size.height);
  } completion:nil];
  </code></pre>
  
  <p>With that code, my child views repeatedly scroll and reset, but the background stays fixed in place. Is it possible to specify a background which scrolls with the view instead?</p>