> On Mar 30, 2015, at 5:17 PM, Daryle Walker <dary...@mac.com> wrote: > >> On Mar 30, 2015, at 7:59 PM, Kevin Perry <kpe...@apple.com >> <mailto:kpe...@apple.com>> wrote: >> >> -replaceItemAtURL:… relies on the atomicity of the POSIX rename() function >> in order to safely do its operation. Since rename() doesn’t work across >> volumes (returning EXDEV), the two URLs must be on the same volume. >> >> If you’re using a temporary directory with replaceItemAtURL:…, you want to >> use -[NSFileManager >> URLForDirectory:inDomain:appropriateForURL:create:error:] with >> NSItemReplacementDirectory, passing it the to-be-replaced item URL. This >> will get you an appropriate temporary directory on the target volume to >> ensure -replaceItemAtURL:… won’t fail due to rename's EXDEV. >> >>> On Mar 30, 2015, at 4:44 PM, Daryle Walker <dary...@mac.com >>> <mailto:dary...@mac.com>> wrote: >>> >>> NSFileManager’s “- moveItemAtURL: toURL: error:” method does a copy if the >>> source and destination file-URLs are on different volumes. Does “- >>> replaceItemAtURL: withItemAtURL: backupItemName: options: resultingItemURL: >>> error:” do similar? The docs for the latter don’t mention it. I’m worried >>> since those docs do mention temporary directories, that we have to do >>> different-volume detection (possibly harder than in the pre-X days) and >>> copying manually. I don’t want to do that, since Apple already includes >>> that logic in the former method. > > So I have to: (1) call URLForDirectory… to make sure there’s an appropriate > temporary directory, (2) call moveItemAtURL… to relocate the downloaded file > from the volume NSURLSession used to the one made in the first step, and (3) > call replaceItemAtURL… for the final move, right? Is there a way to easily > determine if two file objects are in the same volume, to skip the second step > if unneeded? (Or is there a way to tell NSURLSession which volume to put its > temporary files in advance?…)
I’m not personally familiar with NSURLSession, but don’t see any API to specify a volume/directory for the download destination. You can check if two URLs are on the same volume by comparing values for NSURLVolumeIdentifierKey. If they are on the same volume, you can probably skip both (1) and (2). The API doesn’t require a specific temporary directory to work. > > — > Daryle Walker > Mac, Internet, and Video Game Junkie > darylew AT mac DOT com > _______________________________________________ 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
