What are these yellow spacers in Xcode?

Question

Just came back to my desk and Xcode keeps highlighting/underlining white space in files. If I type something it goes away, but if I switch tabs and come back, they reappear.

UPDATE: this isn't caused by the "show invisibles" option. That looks different (try it).

Answer 1

You seem to have a search active. Look in your search bar at the top and you should find a " " character. Xcode is highlighting all instances of the matching space character.