Drift Sumi-e is live in the app store! Download it here!

We had a fairly standard setup for submission, in that we had a separate machine for development and another for submission. Nearing submission day, the question came up of how to transfer the project from one to the other, and for reasons I won’t go into, SVN wasn’t an option.

So using a flash drive, I copied the project over to the submission machine and made a clean distribution build. The first thing that was off was that I wasn’t able to zip the app using the finder’s compression tool. It just hung around 95%. At first, I didn’t think much of this — I’ve been plagued with problems using this tool in the past. I went back to the trusty console, zipped it there (no problems), and then off to iTunes Connect to submit, which ended up giving us some error like “invalid or corrupt zip”. A clean build didn’t help… something was up.

That something turned out to be a bunch of invisible files contained in a couple of bundles, all starting with “._”. They must have been created silently by the flash drive, as they existed throughout the project (but only the ones in the bundles were causing issues, as they were straight copied into the .app package).

So to all devs out there, my advice is to avoid using flash drives. And if you get unexpected errors with the .app package, have a look for unexpected files.