I have a problem using Xcode 6 beta 4 and iOS 8 simulator. Each time I try to run my project Xcode sends me a "Connection lost" error. I tried to delete and create new simulator, set Command Line Tools for Xcode 6 and still nothing happened. what should I do?
Just try to "Reset the content and Settings..." in iOS Simulator, it works for me. Currently my Xcode version is 6.0 (6A313).
This should be a known bug of iOS Simulator after searching, you could try the above the solution to fix it temporarily. Good luck!
UPDATE: Before you try to reset the iOS Simulator, just quit (cmd + Q) and launch it, I found it works good in my simulator/xcode 6.1.1, too.