Re: Does "- replaceItemAtURL: withItemAtURL: backupItemName: options: resultingItemURL: error:" handle cross-volume moves?
Re: Does "- replaceItemAtURL: withItemAtURL: backupItemName: options: resultingItemURL: error:" handle cross-volume moves?
- Subject: Re: Does "- replaceItemAtURL: withItemAtURL: backupItemName: options: resultingItemURL: error:" handle cross-volume moves?
- From: Kevin Perry <email@hidden>
- Date: Mon, 30 Mar 2015 16:59:11 -0700
Hi Daryle,
-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.
-KP
> On Mar 30, 2015, at 4:44 PM, Daryle Walker <email@hidden> 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.
>
> —
> Daryle Walker
> Mac, Internet, and Video Game Junkie
> darylew AT mac DOT com
>
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