Sometimes, it seems I can\'t comment my code with the usual shortcut (command + /) under Xcode 8 Beta 4. The option is disabled in the menu (screen
This bug also happens on Xcode 8.2.1 (8C1002) of macOS 10.12.3 (16D32). And there is another Xcode 7.3, which is fine, also installed on my machine.
I find two solutions:
1. Type sudo /usr/libexec/xpccachectl in Terminal, then reboot.
2. rename the Xcode 8.2.1 to Xcode8,restart Xcode8, now it works!