Set this to thin the packages for one or more devices in Xcode when exporting IPA by methods other than App Store.

Available options are:
<none> (Xcode export non-thinned generic application),
<thin-for-all-variants> (Xcode export universal applications and all available thinning variants),
Or for a model identifier a specific device (eg "iPhone 7, 1").
The default is <none>.