&gt;I wish I could have been a fly on the wall when they were discussing ARC versus GC.<p>Apple shipped a tracing GC (RC is a form of GC) for a while, but couldn&#x27;t get it to work reliably or with adequate performance.  ARC was a bit of a &quot;Hail Mary&quot; and is problematic in its own right, but certainly better than the GC it replaced.<p>Marcel