I'm using PromiseKit in my project, which I've installed through Carthage. (I don't think my issue is specific to either of these, but that's the context) and the project builds fine. But the code editor in XCode highlights errors every time I use a Promise, saying that it is a use of an undeclared type.
The test target in the very same project doesn't have this issue - it can see the Promise types, constructors etc. just fine. So clearly I've broken something, somewhere in the course of setting this up. Does anyone know what build settings might cause something like this to happen, and what I should reset them to?