[Osmium]

> I'm not sure why this is news otherwise.

One reason is that, I believe, currently if even a single 32-bit app is loaded on a newer iOS device, all the standard 32-bit libraries have to be loaded into memory as well which causes increased memory pressure. This is a problem given that current iOS devices only have 1 GB of RAM. Getting older apps migrated to 64-bit is therefore a big deal for this reason alone.

[wvenable]

I think HN has trained me to be very pessimistic about technology news. When I see a link posted like this without much commentary voted to the front page my first reaction is that it must be bad news.

[bradleyland]

If you pick up anything from HN, please don't let it be the pessimism :)

[marvy]

If they only have a gig of RAM, why does iOS bother with 64-bit support at all? Doesn't that increase memory pressure due to all the pointers being twice as big?

[Osmium]

It's a bit more complicated than that. There's a really good discussion here:

http://www.sealiesoftware.com/blog/archive/2013/09/24/objc_e...

and here:

https://www.mikeash.com/pyblog/friday-qa-2013-09-27-arm64-an...

Basically, as I understand it, 64-bit pointers on iOS can actually act to decrease memory pressure because the extra bits can be used to store object class information that would otherwise have to be stored separately.

[marvy]

Thanks!