Since Apple no longer loads 3rd party plugins (in Xcode 8 and above), we have to make change to it. What we have to do overall is to re-codesign Xcode. This allows us to load 3rd party plugins. Here are the steps to do so:
Prepare code sign certificate
2.1 Open "Keychain Access" (in Applications -> Utilities) and select "login" in the left pane.
2.2 Select Create a Certificate ( in KeyChain Access -> Certificate Assistant )
2.3 Input your name (whatever you like) and select "Code Signing" for Certificate Type. Not required but the name is used later in a command line so it could be better to use easily distinguishable name here (I use XcodeSigner here).
Now you have a certificate to code sign.
Then in a terminal,
$ sudo codesign -f -s XcodeSigner /Applications/Xcode.app (Replace the Xcode path if it is different.)
This should take a while.
Go to XVim directory you cloned and build it as usual (Read INSTALL section in README.md).
A self-signed root certificate has a short expire date (1 year). Please check expire date of your certificate
XcodeSignerin Keychain Access App. If it expires, please re-create it.