From Xcode:

2015-06-13 18:51:00.339 MyPlayground[60297:2598943] *** Terminating app due to uncaught exception 'XCPShowViewLimitExceeded', reason: 'Too many live views. The limit is 1 simultaneous live view.'

Simulator output is now directly integrated into the assistant view. For the most part it works great and runs more smoothly and less migraine-inducingly than earlier versions.

On the other hand, sometimes there’s this: