I recently installed XCode 8.3.3, and am working on a Swift 3 project within it. The symbol navigator, in which I'm used to seeing all foundation classes, only ever shows my app classes. It does not show any of the Cocoa/Foundation classes. Furthermore, there is another problem which I think relates to the above problem ... I'm unable to simply open a foundation source file, such as, for instance, AVAudioRecorder.h, even though it shows up in the search list when I do Shift + Command + O. I try to open it, and it shows me an error (image attached) "Couldn't generate Swift representation". I searched online for solutions to the Swift source problem, and cleaned my "Derived data" folder. All that did was make me a few seconds older. Please help ! Thanks ! Images attached.