"Check Spelling While Typing" grayed out
I'm trying to spell check static strings in my code. I've searched stackoverflow with no useful results (e.g. refers to outdated version of Xcode or just no answers). I just installed the latest update of Xcode (version 9.2) and it still doesn't work (i.e., the option is grayed-out).
Ignore greyed out button and press CMD+; anywhere inside the code editor. The greyed options will now be enabled.