I'm using AppCode 2017.3 EAP (Oct 17) and Xcode 9.0.1.
I'm not sure if it's when we switched to using an xcworkspace instead of an xcodeproj, or if it's when I upgraded to Xcode 9, but for the past several weeks AppCode is showing several errors/warnings in every file and Xcode is showing none of these.
(AppCode does compile/run w/o any issues.)
A lot of the errors are like this:
"Can't resolve variable title"
NSString* title = nil;