title: Mac App Store: Giving up 32 bit support in favor for ARC, will existing users of 32 bit version see an update message?
body: <p>I'm considering dropping 32-bit support for in favor for Automatic Reference Counting (which is only supported for 64 bit binaries).</p>
  
  <p>I'd like to avoid these two scenarios with the Mac App Store:</p>
  
  <p>For a <strong>user of an old 32-bit Mac</strong>:</p>
  
  <ol>
  <li><p><em>who did purchase the previous version with 32-bit support:</em> Will they see an update message for the app in the Mac App Store? If so, the (now 64 bit only) update would not work for him/her.</p></li>
  <li><p><em>who has not purchased the app before:</em> will they be able to purchase the app although it will not run on their system? </p></li>
  </ol>
  
  <p>ARC 64 bit only:
  <a href="http://developer.apple.com/library/mac/#releasenotes/ObjectiveC/RN-TransitioningToARC/_index.html#//apple_ref/doc/uid/TP40011226" rel="nofollow">http://developer.apple.com/library/mac/#releasenotes/ObjectiveC/RN-TransitioningToARC/_index.html#//apple_ref/doc/uid/TP40011226</a></p>
  
  <p>EDIT:
  I found one occasion of somebody being able to download a <em>64 bit only app</em> to a 32 bit MacBook and being presented with an error message <strong>"Your purchase could not be completed"</strong>. In this case it was a free app. I wonder when this message would pop up for a paid app (before or after the payment).</p>
  
  <p><a href="http://www.linethirteen.com/blog/2011/01/mac-app-store-32-bit-vs-64-bit/" rel="nofollow">http://www.linethirteen.com/blog/2011/01/mac-app-store-32-bit-vs-64-bit/</a></p>