For some reason, in Xcode 8.2 my code completion has stopped working. I have cleaned my product, restarted Xcode, restarted my computer, and deleted the derived data, and still no luck. I have submitted this to Apple Support. Has anyone run into this before and been able to fix it?
Update: As per @Dareon solution below also works for Xcode Version 8.3 (8E162) and 8.3.2 (8E2002). Thanks, @Dareon for the confirmation. :)
I was facing the same issue and following worked for me.
I am using Xcode Version 8.2.1 (8C1002).
At least, it worked for me.