TT's Zip Archive Package can now read Apple's > 4GB zips

I recently improved my Zip classes for Xojo so that they can read zip files that are created by Finder (or by Apple’s “ditto” tool) and are over 4 GB in size.

Most unzip apps, including the ones on macOS and Linux, can’t unzip these, but my code can, now.

It may even be able to write them back out, but I haven’t tested that thoroughly, yet (you’re welcome to try and report back to me).

I have not released that new version, yet, because, well, it’s not too well tested, but it did well enough for the recent need I made it for.

Is there anyone here who uses my code and needs this? And would do some more testing? Then get in contact, please, or comment here.


I used to use your Zip code, but have moved to MBS to get files > 4GB. I still have two issues that I hope you have resolved:

  1. Can you add an empty folder (my zip files ignore, and thus leave out, empty folders)?
  2. Can you add an alias to a zip file (my zip files resolve all aliases)?
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Can you add an empty folder

I handle this in one of two ways
1/ When the app starts if a folder doesnt exist, I create it
2/ Have a 1byte info.txt file in the folder to force it to be created

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We have >2 GB in MBS for a long time.
But not all applications understand the 64-bit extension for zip format.

By using the zip64 format, or can the MBS plugin also decode Apple ditto’s large zips? Mine can the latter but not the former.

You mean when creating Zip files? Not sure, but shouldn’t be difficult to do.

Yes, by using the MacBinary option when adding that particular item.