Now don't get me wrong, I'm normally of the opinion that anything that whiffs of manual memory management is for chumps. But by day I write apps that target workstations that have enough RAM that I can get away with pretending that memory is an unlimited resource.

On a memory-constrained platform like iOS, though, being able to tightly control how much memory you're using becomes much more valuable. If not critical. And the one place where garbage collection simply can't beat manual memory management is total memory consumed. All those dead objects that are waiting around to be scooped up by the collector do take up space. Sometimes a whole lot of it.