Universal builds for Mac App Store with Xcode Feb 03, 2011
While working on Wallpapery, I had to do a universal build for both 32- and 64-bit. I expected I should simply set "Architectures" to "Standard (32/64-bit Universal)" but after approval in Mac App Store and user complaints I found out, I had missed a couple of steps.
To build your product for both 32- and 64-bit architectures (aka i386 and x86_64) you have to explicitly unmark "Build Active Architecture Only" and filter list of "Valid Architectures" to only list "i386 x86_64"
I wasn't aware of that so maybe others find this useful.