There is a new autocomplete in Xcode. Probably might be useful because it checks not only beginning of names etc. But I found that very often it doesn\'t find a class name o
I have the impression that some 'parts' of autocompletion simply fail after a while. I use to restart the Mac to get it back working. But sometimes it fails quite soon again. Maybe the answer of @Alex Bykov combined with a restart will do the trick.
Anyway: auto-completion of Xcode always was crap. AppCode used to get it much better. Unfortunately not yet with swift.