Getting Warning: Detected a case where constraints ambiguous


I am getting a strange warning and I’m not sure if it’s something that I’m doing or if it’s possible related to something that has changed in iOS 8. I’ve completed all of Chapter 19, when I run it all is well, except for a strange warning.

As far as I can tell, I’ve created all of the constrains correctly. Am I missing something else or is this related to iOS8?

Thanks in advance!