On 22 Sep 2016, at 12:04, John Brownie <john_brow...@sil.org> wrote: > > I find that I am in need of dealing with versions of strings that may be > turned into file names, and thus I need to be comparing normalised forms. > However, according to > https://developer.apple.com/library/content/qa/qa1173/_index.html, "For > example, HFS Plus (Mac OS Extended) uses a variant of Normal Form D in which > U+2000 through U+2FFF, U+F900 through U+FAFF, and U+2F800 through U+2FAFF are > not decomposed (this avoids problems with round trip conversions from old Mac > text encodings)." > > Is there a way to get at this variant? [NSString > decomposedStringWithCanonicalMapping] returns "A string made by normalizing > the string’s contents using the Unicode Normalization Form D." That seems not > to give what I need, but I haven't seen a better option. Is there such a > method?
This is rather a hairy problem, actually. You don’t know that the filesystem is actually HFS+. The filename in question could refer to a file on an NTFS volume, or (in future) an APFS volume. It could also be a network filesystem, which could be mounted on a system running a completely different operating system with unknown character encoding behaviour; typically UNIX behaviour, for instance, is to completely ignore the filename encoding problem and treat filenames as a string of bytes (thus you are free to interpret them as UTF-8 if you so wish, but the filesystem will regard U+00E9 as different from U+0065 U+0301, even though the two names will display the same on screen). Additionally, the version specified in HFS+ was based on a particular version of the Unicode standard (I forget which), but importantly *not* the current version, which is what the NSString APIs will use. Perhaps we should start by understanding the context of your question. Is there a specific reason you want to match the filesystem behaviour precisely? Kind regards, Alastair. -- http://alastairs-place.net _______________________________________________ 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
