I had the same crash but it occurred when accessing the auto-generated initializer for a struct. I'd do a clean, and then build, and it would crash with an "exc_bad_access" code=2. The stack trace ends with a call to libswiftCore.dylib`swift_retain I'd then manually code the initializer and it'd be fine. If I commented out the code, without cleaning, it'd still be fine which was odd. But if you clean it again, and then build it using the auto-generated initializer, it'd crash again. It seems that the auto-generated code is causing some issues. This also seems to be the case for codedby.pm too as he discussed changing a property from: public private(set) var foo: Bar to: public var foo: Bar removed the crash.