I'm surprised that Apple released the new Core Data guide with examples written only in Objective-C. I've been thinking in Swift idioms now for a while and it's hard to go back and forth. Please release the guide with Swift sample code.
Why was the new Core Data guide only released with Objective-C code?
Just so you know, it's perfectly fine for us developers to submit bug reports or enhancement requests about the documentation.
Remember, Swift is still very young. Formal docs will come in time, but right now, natural flux (and hi freq. edits) would create risk and time/resources wasted towards otherwise controlled documentation.