Maybe I'm blind, but I don't see a way to search within a file (⌘F) matching whole words only. (The functionality still exists for finding within multiple files.) I use this all the time to find identifiers or numbers; am I missing something, or is the feature disappearing for some reason?
How to search matching word in Xcode 9?
Probably a bug.
Workaround by using a regex search and the \b word boundary metacharacter.
To find "Foo": \bFoo\b
To find "123": \b123\b