On creating Fat framework from aggregate target, I am following the build phase script from this gist link with minor changes on my script link.
On target build, Xcode is showing fetal error: lipo: can't create temporary output file: /${PROJECT_NAME}.framework/${PROJECT_NAME}.lipo (No such file or directory)
See image below for reference

Follow below steps:
Simply copying below script in
Run Script, your workspace returns fat binary for me.This worked for me so far.