On Feb 26, 2013, at 12:47 PM, Gerriet M. Denkmann <gerr...@mdenkmann.de> wrote: > My investigations regarding archiving on OS X: > > 1. NSArchiver stores all strings in Utf-8. > This is inefficient for strings which contain mainly non-european > characters (e.g. Chinese or Thai) as one character will use 3 bytes (Utf-16 > would use only 2). > Corollary: It cannot store strings which contain illegal Unicode chars.
And then in UTF-16, strings which contain mostly ASCII/European characters are wasting 2x space. Six of one, half dozen of the other. This is a very old debate and I'm grateful that Apple chose UTF-8 for storage, as UTF-16 makes things much more complicated. > 2. NSKeyedArchiver seems to be ok. > But it does create unnecessary data. E.g. in the case of an array > containing identical objects, like: > NSArray *a = @[ @"a", @"a", ...., @"a"]; > With 1 000 000 items it creates 10,000,395 bytes - my version creates > only 1 000 332 bytes > and the output is still readable by NSKeyedUnarchiver. Are you sure this is happening? NSKeyedArchiver is documented as doing deduplication of objects. If this is true, it's definitely a bug and there is no reason Apple wouldn't want it fixed. > 3, NSKeyedUnarchiver has several bugs. > The string $null is converted to nil. > Very harmful if this string is part of a collection (like array, set or > dictionary). It should have already been mangled by NSKeyedArchiver. > If the key in: encodeXXX:forKey: starts with an "$" NSKeyedArchiver > correctly mangles this by prefixing > another "$". But NSKeyedUnarchiver does not find these mangled keys and > returns nil or 0. You can, as a workaround, consider keys prefixed by $ as reserved, however this is certainly a bug. The fact that no one has reported it/gotten it fixed in so much time shows that it's probably not a major issue, though. > I have not reported these bugs, as I am convinced that Apple has no interest > in fixing these problems. This is the exact attitude that causes Apple to be perceived as not having interest. Please file the bugs - the engineers reading this list can't give high priority to things that developers don't report, as much as they'd probably like to. -- Gwynne Raskind _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
