title: How does the app-update process in the Apple AppStore work
body: <p>I managed to squeeze down texture/image data for my game to 20mb to allow 3G downloads. I would like to stay below 20mb, even if my app gets updated (additional texture data). In order to allow future updates, the app copies all textures/images from the main bundle to the Documents directory (which is not altered when an app is updated). When the app starts, it checks if the required textures exist in the Documents folder. If they dont exist, textures are copied from the main-bundle to the document directory.
  My updates should only contain new texture data (which is again copied to the document folder) and a modified binary. Is this possible? How does apple update ios apps? My approach only works, if updates are applied sequentially when a user decides to update an app:</p>
  
  <p>1) original version is installed
  2) update available -> install
  3) update available -> install
  ...</p>
  
  <p>The described approach will not work, when apple only provides the "latest" version (because all previous updates are missing).</p>
  
  <p>I hope somebody can shed some light on the update process.</p>
  
  <p>thanks</p>