Why are Preview/Replace buttons disabled in Find & Replace in Project

Question

I've no idea what else it wants me to do... or why it isn't working.

Answer 1

Yes, it's not the most intuitive nor the most well-documented thing and it took me a few minutes of researching and fiddling around within Xcode myself to figure this out for you.

Click enter or return while your cursor is in the "Find" field in order to find all the things you are going to replace.

You'll see the list of found strings, and only at that point, that's when the "Preview" and "Replace" buttons will enable.