Code sensing and color issue

I am having a weird problem, my xcode stopped changing the color of my decl开发者_运维问答ared method name and variables(it is still auto-complete the name), all the name appeared to be black rather than purple, it runs just fine, but it is difficult for future debugging, I've checked the Xcode Preference->Fonts and Colors, from Project Class Names to the end it appears as grayed out, seems not available. I've googled a lot but no luck.

Thanks in advance!

Was it something like this?

For me the solution (which I lucked-upon, rather than deduced) was to close Xcode and restart it. It must be a bug in Xcode.